Install the Latest Version of macOS

If your Mac is already running the latest version of macOS, good for you! Skip to Turn On Automatic App Store and macOS Updates (next). If not, your first step should be to upgrade.

All Macs introduced in 2012 or later—and even some introduced as long ago as 2010—can run macOS 10.14 Mojave. (And, frankly, if your Mac is more than seven or eight years old, you might want to think about buying a new model.) Since Apple no longer charges for operating system upgrades and your Mac most likely supports the latest version, you should seriously consider installing the latest version of macOS that will run on it. (Even if your Mac doesn’t support Mojave, it might still support the previous version of macOS, 10.13 High Sierra.)

Every release of macOS includes dozens if not hundreds of bug fixes to prevent crashes or other errors and to patch security holes. That fact alone is reason enough to keep up to date. In addition, Apple constantly introduces useful new features, and some newer software runs only on recent versions of the operating system. Often, doing nothing more than updating your system software can eliminate a wide range of problems—and prevent others.

Operating system updates fall into two categories: major and minor. Major updates (more properly known as upgrades) change the operating system’s name (as in High Sierra and Mojave) and increment the digit(s) after the first decimal point in the version number: 10.0, 10.10, and 10.14 were all major updates. Minor updates change the number after the second decimal point; for example, 10.14.1 and 10.14.2 were minor updates.

You should always download and install every minor update, because minor updates focus on bug fixes. (However, I suggest waiting a few days after a macOS update appears to make sure it doesn’t contain any serious errors; see Check for Software Updates, later.) The easiest way to do so is to use the automatic update features in the App Store app and, if applicable, the Software Update pane of System Preferences (see Turn On Automatic App Store and macOS Updates, next). Major upgrades are less urgent, especially when they focus on new features; nevertheless, since they also fix numerous bugs, you should install them as soon as it’s convenient. Read New Releases of macOS, later, for details.

Some Mac users, having heard horror stories of half-baked releases that cause as many problems as they fix, feel anxious when software updates appear. Major errors can sneak into system updates, but this happens rarely, and usually Apple resolves such problems promptly. In addition, many errors that appear to be update-related are in fact the result of existing problems on the user’s Mac, minor issues such as outdated third-party apps, or even (gasp!) user errors. I can’t guarantee a software update will never break anything, but in my experience the benefits of updates overwhelmingly outweigh the risks—especially if you maintain good backups (see Set Up a Backup System).

Turn On Automatic App Store and macOS Updates

You can check for and install updates to all Apple apps, and many third-party apps, using the App Store app. Starting in Mojave, the Software Update pane of System Preferences, which you can use to manually update macOS, also lets you configure automatic updating of those apps, as well as of macOS itself. (Under High Sierra and earlier, the App Store pane of System Preferences serves that purpose.) Although you can manually update using the App Store app and System Preferences > Software Update at any time, setting up your Mac to update software automatically is the easiest way to keep your Mac up to date with bug fixes and minor enhancements.

After you install macOS, it prompts you to turn on automatic updating. Whether you remember doing that or not, you should confirm that it’s on and that it’s configured optimally.

How automatic you want to make updating is up to you. I recommend that you decline automatic updates to macOS itself, and that you give careful thought to whether you want the App Store to update individual apps without intervention. (In both cases, you might feel safer making this a weekly task; see Install App Store Software Updates.) However, downloading updates automatically and displaying alerts when updates are available is certainly a good idea.

Although the instructions are similar for Mojave and for older versions of macOS, they’re different enough that I list them separately below.

Update Third-Party Software

Software bugs are a fact of life, but in general, apps improve with each release. You can avoid, or solve, many problems by making sure you have the latest version of every app installed.

Clean Out Accumulated Cruft

The term “cruft” is hacker slang for digital detritus—obsolete, extraneous, or otherwise useless files that have accumulated on your disk over time and now do nothing but take up space. By removing cruft, you can recover valuable disk space; increase the efficiency of Spotlight searches, backups, upgrades, and disk diagnostics; and reduce the chance of software incompatibilities.

What counts as cruft and how much of it you should remove are somewhat subjective matters. Before I get into specifics of what to delete or how, I want to expand a bit on the goals of this step:

• Avoid running low on disk space. macOS requires breathing room for writing temporary files, using virtual memory (in which a portion of your disk substitutes for physical RAM), and other tasks. If your disk is nearly full, your overall performance may deteriorate sharply as macOS runs out of room for these files. (This deterioration is far more pronounced with hard drives than with SSDs.)

  I want to emphasize that this condition occurs only when you’re quite low on disk space. How low is “quite” low? My rule of thumb is that the available space on your disk (see the sidebar How Much Disk Space Is Really Available?, next) should always be at least 6 GB or twice the amount of RAM installed, whichever is larger. (But, once you get to about 100 GB of available space, I’d say you’re in good shape regardless. If you have, say, 128 GB of RAM in an iMac Pro with 1 TB of storage, it’s a bit unrealistic to keep 256 GB of storage space free!) If you have hundreds of gigabytes (or more) of free space, then regardless of how many files are on your disk, deleting files won’t have a noticeable effect on overall performance.

  Of course, you fill up more disk space as you use your Mac, so it’s best to leave an extra margin of error so that you aren’t constantly bumping into the danger zone. Suppose that your Mac has 8 GB of RAM, that you therefore want to have at least 16 GB of free space on your disk, and that you currently have 20 GB of free space. That’s enough for now, but download a single HD movie and you’ll be in trouble again. So I suggest clearing enough space that you can use your Mac normally for a month or more without hitting your limit.

• Increase efficiency. Suppose you do a Spotlight search for a certain term and it turns up thousands of matches, but most of those matches are useless files—downloads you no longer need, duplicate files, obsolete versions of documents you’ve since updated, and so on. Now you have to waste time wading through those matches to find the item you want. If your disk contains fewer of the files you’re sure you’ll never need, every search you perform can be more efficient.

  The same goes for other common tasks. Backing up your disk—and finding files in your backups when you need to restore missing data—can take much longer than it should if you have lots of extraneous files. When you upgrade to a new version of macOS, run disk utilities, or migrate to a new Mac, the more files there are, the longer these processes will take. If many of these files are superfluous, getting rid of them can increase your efficiency and that of numerous apps and tasks.

• Avoid software incompatibilities. I don’t know about you, but I download new software constantly—especially system enhancements such as preference panes, status menus, and other utility apps and background processes. Often I just install a demo version to try it out for a few days, lose interest, and forget about it. Then, months or years later, I upgrade macOS and find that something doesn’t work right because a third-party app I installed a long time ago isn’t compatible with the new version of macOS (or with other software I’m actively using). By deleting stuff you’re no longer using, you reduce the chances of such incompatibilities.

  Another reason to delete unneeded software is performance. If apps are running in the background but you aren’t actively using them, they’re still using up RAM and CPU resources, which means they can slow down the other activities you use your Mac for.

  Because I’ve written quite a few books about upgrading macOS (see Buy Take Control of Upgrading to…) and have encountered many such software conflicts during my testing, I always recommend de-crufting as part of one’s upgrade process. But an even better idea is to weed out any software you don’t need—right now and as a yearly task. In addition to avoiding incompatibilities, you’ll free up the disk space used by those apps; and, if they were running in the background without being used, you may also improve your Mac’s performance.

To summarize, if you’re running low on empty disk space, eliminating cruft is crucial. But even if you have tons of free space, you can improve your Mac’s efficiency and performance by deleting unnecessary items—especially unused apps (as opposed to user-created files).

Turn Off Unneeded Login Items

macOS can run apps or open files automatically when any given user logs in; items set to open in this way are called login items. You can add a login item manually—for example, to save yourself a click or two by making sure your favorite apps run every time you log in.

Numerous apps also install login items—often without advertising that fact—so that background services they rely on are always available. Examples of apps that install background-only login items are Backblaze, BusyCal, Dropbox, and LaunchBar.

Login items are useful, but they can also increase the time it takes to start your Mac (or switch users). In addition, the more apps you have running at once, the greater your RAM Usage and CPU Load. So I recommend checking to make sure you don’t have any login items you can do without.

To check your login items, follow these steps:

1. Go to System Preferences > Users & Groups.

2. Select your account in the list on the left, and click Login Items (Figure 5).

   

3. Scan the list of login items for any you no longer use. If you find one, select it and click the minus button. Repeat as necessary.

   Clicking this button removes the item from the list but does not delete the corresponding item from your disk.

Set Up a Backup System

No amount of maintenance can guarantee that your disk will never crash, that your Mac will never be stolen, or that lightning will never strike your house. Any number of catastrophes could potentially imperil your computer and its data. Of course, you can replace a computer, but what about your email, photographs, music collection, tax records, and all the other important information? To keep your data safe, you need good backups. If you’ve never taken the time to set up a proper backup system, the time is now!

I wish I could tell you that backing up your computer effectively is a simple matter of clicking a few buttons. But there’s more to it than that: understanding the various types of backup, choosing backup hardware and software that has all the features you need, configuring your system, storing backup media safely, and many other details. The good news, though, is that once you’ve set up a backup system, it should run happily with little intervention for months or years.

Because so much can be said about backups, I’ve written an entire book on the subject: Take Control of Backing Up Your Mac. If you have any doubts or questions about backing up, I recommend giving it a read. I think you’ll find it to be time (and money) well spent.

Although I can’t cover everything in the Backing Up book here, I can give you a brief summary. For the best compromise among data safety, cost, and ease of use, I generally recommend the following:

• Versioned backups: Backups that include previous versions of your files, and files you’ve deleted. Time Machine is one way to get these, but there are dozens of other options too, including ChronoSync, Retrospect (that is, Retrospect Solo for individuals, or Retrospect Desktop for small businesses), and QRecall.

  Whichever app you use, it should store your backups on an external hard drive. If your backup app doesn’t automatically back up your Mac on a fixed schedule (such as once an hour) or continuously (whenever files change), make sure you schedule backups to occur automatically at least once a day; more often is better.

• Bootable duplicate: On a second partition of your backup drive (or on another external drive), make a bootable duplicate (also called a clone) of your entire hard disk onto an external drive and update it at least once a week. Data Backup can make duplicates as well as versioned backups; Time Machine, Backblaze, and QRecall cannot. Two apps that specialize in bootable duplicates are Carbon Copy Cloner and SuperDuper!.

• Offsite storage: Store an extra backup somewhere far away from your Mac, so your data is still safe if your house burns down, your office is burglarized, or some other catastrophe wipes out your Mac and all your other equipment.

  One way is to have a second physical backup drive. Store one drive in a safe place (such as a friend’s house or a safe deposit box), and once a week or so, swap the drives.

  As an alternative to physically moving drives offsite, consider using an inexpensive internet backup service that securely stores an extra copy of your files on a secure server. Examples include:

  • Backblaze ($5 per month per computer)

  • IDrive ($69.50 per year for 2 TB of storage)

Needless to say, you can back up your Mac in many other ways, and you can learn more by reading my Backing Up book. But one way or another, get a backup system in place right now. Later in this book, I reiterate important backup tasks: Update Your Versioned Backup (daily); then Update Your Bootable Duplicate and Rotate Physical Backups Offsite (weekly), and Test Your Backups (monthly). If you set everything up now, you’ll breeze through those periodic tasks, almost without noticing them.

Test Your Hardware

Apple Diagnostics is an unusual program that performs a series of diagnostic tests on your Mac’s hardware, including the AirPort card, logic board, hard drive, RAM, and video RAM. It doesn’t repair anything, and it doesn’t look for problems such as directory errors that are the province of Disk Utility (see the next topic, Run Disk Utility). But it can identify subtle hardware defects that could later lead to serious problems. (Macs shipped prior to June 2013 used a similar tool called Apple Hardware Test, which was more comprehensive but slower and rather homely.)

Whether your Mac is fresh out of the box or years old, you owe it to yourself to make sure its major components are in good health, and this is the easiest (and cheapest) way to do so.

Apple Diagnostics (or Apple Hardware Test) comes in customized versions for every Mac model, and can run only from an external boot drive (such as a DVD or a USB flash drive), from the invisible Recovery HD volume installed as part of macOS, or (on newer Macs only) over the internet. Even if you could manage to copy it to your local disk or SSD, it wouldn’t run from there.

If you purchased your Mac before mid-2011, when 10.7 Lion was released, your Mac should have included external media with Apple Hardware Test on it. Depending on your Mac model, Apple Hardware Test may be included on the OS X Install Disc 1, the Applications Install Disc 2, the USB Software Reinstall Drive, or some other disc with a similar name. (Look for tiny lettering that says, “To use Apple Hardware Test, hold down the D key as the computer starts up.”) If you have such a disc or USB drive, find it now.

Shortly after Apple released Lion, the company began shipping new Macs without any external boot media at all. These Macs can still run Apple Hardware Test but normally do so from a special disk image hidden on the Recovery HD volume—and if that’s not available, they can run the program over the internet, as I describe in a moment. Apple Diagnostics, like recent versions of Apple Hardware Test, comes on a hidden disk image and is also available to run over the internet if the disk image isn’t available.

To run Apple Diagnostics or Apple Hardware Test, follow these steps:

1. If you have a disc or USB drive with Apple Hardware Test on it, insert it into your Mac; if your Mac shipped after Lion was released and did not include external boot media, make sure the Mac is connected to the internet (via Ethernet) or that a Wi-Fi network connection is available.

2. Choose Apple  > Shut Down and wait for your Mac to shut down completely.

3. Press the power button to turn on your Mac, and immediately press and hold the D key until Apple Diagnostics starts or the Apple Hardware Test chooser screen appears, either of which may take a minute or more. If Apple Diagnostics or Apple Hardware Test can’t be found on any local media and you’re using a Wi-Fi connection, select a wireless network when prompted, and enter its password (if any).

4. Select a language (using the mouse or the arrow keys) and click the right arrow button or press Return. (For Apple Diagnostics, you only need to do this the first time you run it.)

5. For Apple Diagnostics:

   The test runs automatically, and takes just 2–3 minutes. At the end, it either says “No issues found” or lists any problems along with information on what you should do about them.

   For Apple Hardware Test:

   1. On the Hardware Tests tab, if there’s an Extended Test button, click it. If not, select the checkbox Perform Extended Testing (Takes Considerably More Time) and click Test.

      Now kick back with a good book while you wait for the test to complete. The screen may say something like “Estimated time: 10–15 minutes, or longer depending on the amount of memory installed.” If your machine has lots of RAM, “or longer” could turn out to be hours.

   2. If the test uncovers no problems, the Test Results area either displays “No trouble found” or puts the word “Passed” next to all the applicable tests. If a problem does exist, a failure message appears along with advice for what to do next.

6. Click Restart to restart your Mac.

I recommend running the test again after installing RAM or any other new hardware inside your computer, or if you begin to have inexplicable problems that ordinary disk utilities do not solve.

Run Disk Utility

You know the old saying: “If it ain’t broke, don’t fix it!” With computers, though, things can be broken without manifesting any obvious symptoms. You can nip many such problems in the bud with a simple procedure that looks for, and fixes, common disk errors that can crop up over time without your knowledge. (I recommend doing this not only as an initial troubleshooting step but also as monthly maintenance.)

The instructions differ depending on which version of the operating system you’re running.

Use a Surge Protector or UPS

If your computer’s AC cord or adapter goes directly into a wall socket, you’re putting your Mac at the mercy of the power company, your home’s wiring, and all the things that can go wrong in between: brownouts, voltage spikes, lightning, you name it. Your Mac’s power supply is pretty robust, but a single random power surge can still fry its circuits. Even when the electricity appears to be flowing correctly, imperceptible fluctuations in the current can cause computer components to deteriorate more quickly than normal.

So please, take the basic precaution of using a surge protector. However, be aware that not all surge protectors are equally good. In fact, some offer almost no protection at all (and price does not necessarily correlate to quality). Here’s what you should look for:

• A UL (Underwriters Laboratories) label with the words “Transient Voltage Surge Suppressor.” This wording indicates that the device meets the criteria for UL 1449, a performance standard with well-defined and testable parameters.

• A good warranty that covers not only the protector itself but also the equipment attached to it, in the event of a surge. This warranty is perhaps more crucial even than the surge protector hardware itself, because even the best products can sometimes fail.

A surge protector that has neither of these features is probably not worth paying for.

A step up from a surge protector is a voltage regulator (such as the APC LE600 Line-R) or a power conditioner (such as the Furman PST-6). Both types of product include surge protection but also keep the voltage to connected objects steadier (within a narrower range) even when there aren’t surges.

Better still, consider buying a UPS (uninterruptible power supply). A UPS contains a battery with enough juice to power your computer for anywhere from a few minutes to a few hours, along with circuitry to convert the battery’s DC output to AC and switch over to the battery instantly and seamlessly in the event of a power outage. If the power goes out for more than a very brief period, the UPS sounds an alarm so that you’ll know to save your work and shut down your computer safely before the UPS’s battery goes out. (Some UPS units include USB cables that attach to your Mac, allowing you to configure an automated shutdown in System Preferences > Energy Saver > UPS; this pane doesn’t appear otherwise.) In addition to protecting your computer from power outages, most UPS units condition the electricity flowing through it and absorb power surges.

Here are a few examples of reputable UPS manufacturers:

• APC

• CyberPower

• Panamax

• Tripp Lite

Update Weak Passwords

Passwords are a fact of life in the wired 21st century. You probably have dozens or even hundreds of passwords, such as these:

• Your macOS administrator password

• Passwords for iCloud and any other email accounts you may have

• Passwords for websites and other online services

• An administrative password for your Wi-Fi router, and another one for your wireless network

It’s easy to become lazy—choosing short, easy-to-type (and easy-to-remember) passwords and reusing the same password in multiple places. But both of these practices put your security and privacy at risk. Passwords that are simple for you to remember and type also tend to be easy for an attacker (or the attacker’s sophisticated software) to guess. And if you reuse the same password in multiple places, a password breach at one site could leave many of your accounts vulnerable.

I provide extensive advice about choosing, using, and changing passwords—and about utilities to help you with these tasks—in my book Take Control of Your Passwords. (For a shorter overview of password managers, with details on what I recommend and why, see my Wirecutter article The Best Password Managers.) For now, I want to make just three recommendations:

• If you don’t already use a password manager (a tool that generates, stores, syncs, and fills in passwords for you), start now. 1Password (Figure 7) is my personal favorite; other good choices include Dashlane, iCloud Keychain (built into macOS and iOS), LastPass, and RoboForm.

  

• If you use the same password in more than one place, change all those passwords so they’re unique.

• Make sure all your passwords are long and random. (I offer a detailed explanation of how long is long enough, and how random is random enough, in Take Control of Your Passwords.) As a rule of thumb, a 16-character password that contains upper- and lowercase letters, digits, and punctuation—in a random order chosen by a computer—should fit the bill.

Each website, app, or device has its own procedure for changing passwords; I can’t begin to cover them all in this book, but here are a few common places to look:

• To change your macOS user account password, go to System Preferences > Users & Groups. Select your username in the list on the left and click the Change Password button in the Password view.

• To change the password associated with an Apple ID (used for iCloud, iTunes Store purchases, and many other purposes), go to Apple’s Manage Your Apple ID page and log in. Then click Change Password (under the Security heading) and follow the instructions.

• To change the password used by your AirPort base station (or Time Capsule) or your wireless network, open AirPort Utility, which is located in /Applications/Utilities. Select your base station and click Edit, and then click Base Station. To change the base station’s password, enter and verify the new password and click Update. To change the password of your wireless network, click Wireless, enter and verify a password, and click Update.

For even more about the security and privacy implications of weak passwords, read my book Take Control of Your Online Privacy.

Use Optimized Storage

If your Mac is running Sierra or later, one handy way to free up disk space and reduce the rate at which clutter accumulates is to use Optimized Storage features in macOS. With these features, macOS automatically purges outdated caches, logs, and other unneeded system files, and asks if you want to delete downloaded disk images after installing software from them. In addition, you can enable several optional features:

1. Choose Apple  > About This Mac > Storage and click Manage.

2. In the list on the left, select Recommendations (if it’s not already selected). The options available to you will vary based on which settings you’ve already selected, but by default, you can opt for any or all of the following:

   • Store in iCloud: To move your Desktop and Documents folders to iCloud Drive or enable optimized storage of your iCloud Photo Library (or both), click Store in iCloud, select one or both of the checkboxes, and follow the prompts.

     If you select Desktop and Documents, those two folders will be moved to iCloud Drive (and thus copied to Apple’s servers); if you enable this feature on other Macs, those folders will sync with the other Macs too. macOS automatically removes older files from your Mac if you start running low on disk space—but the files’ icons remain in place, and if you attempt to open the files later, macOS downloads their content automatically. (Note that if you choose this option, you may need to purchase additional iCloud storage from Apple.) Before you enable Desktop and Documents, think about how much space the items in those folders occupy and the impact of syncing them on your iCloud storage space and your internet provider’s data cap, if any. You may find, as I do, that space and financial considerations lead you to forgo this option.

   • Optimize Storage: Click Optimize and follow the prompts to instruct macOS to remove from your disk any movies or TV shows from the iTunes Store that you’ve already watched (you can download them again later if you like, as long as they’re still available from Apple). You can also have Mail download only recent attachments, or no attachments at all—again, those can be downloaded on demand if needed.

   • Empty Trash Automatically: Click Turn On (and confirm by clicking Turn On again) to have macOS automatically remove items from your Trash that have been there for 30 days.

   • Reduce Clutter: Click Review Files to show large files, downloads, and other items you might want to delete.

Once you’ve enabled any of these features, macOS will perform the necessary tasks in the background from then on. You’ll be less likely to run out of disk space, but Optimized Storage does not by any means eliminate the need for other types of manual maintenance.

Consider Maintenance Utilities

You can perform nearly every maintenance task I discuss in this book manually—for example, by dragging certain files to the Trash or using utilities built into macOS such as Disk Utility and Terminal. On the other hand, there are numerous third-party utilities that make it quicker and easier to perform many of these tasks, and you might be able to save yourself considerable effort by using them.

Before I tell you about a couple of my favorite general-purpose utilities, however, I want to urge you to exercise skepticism and restraint.

If I believed that merely running an app were the answer to all your Mac’s maintenance needs, I wouldn’t have bothered writing a whole book on the topic! Although maintenance apps can be quite useful if you know what you’re doing, they can also cause harm if used injudiciously—removing essential files and slowing down your Mac (which is, of course, the opposite of what they’re supposed to do). So I want you to choose utilities carefully and use them with both eyes open.

Here are some important facts to keep in mind when evaluating and using maintenance utilities:

• Free disk space is not a panacea. I’ve read countless claims that one app or another will speed up your Mac, solve numerous random problems, and keep your disk healthy simply by freeing up disk space. Don’t believe it! Although it’s true that your Mac can slow down if free disk space becomes critically low (as I explained in Clean Out Accumulated Cruft), above a certain amount of space there’s no direct correlation between free disk space and performance. For example, if you have a 500 GB hard drive with 495 GB occupied and 5 GB free, that is indeed a problem. But if you have a 3 TB drive with 495 GB occupied, you have over 2.5 TB free, and deleting files won’t improve your performance at all (although, admittedly, there are other good reasons to delete files).

• Don’t throw out the baby with the bathwater. There are valid reasons to delete caches (see Consider Clearing Certain Caches), logs, browser cookies, unneeded language resources, and other such items. But these files are not inherently problematic. Some utility developers want you to believe that all this stuff is nothing but clutter that bogs down your Mac, and that you should delete it all at every opportunity. Please don’t! As I discuss later, you should be highly selective in what you delete and when; regularly deleting all your caches, all your cookies, and so forth is a waste of time, and largely futile. It rarely solves problems, it might reduce your performance, and your Mac will recreate most of that stuff anyway.

• The default settings are almost always wrong. If you find that you need to delete certain apps or files and you want to use a utility to help you do so, by all means, go for it. But most maintenance utilities have a zillion options that are selected by default—the assumption being that you’ll trust the app to do the right thing—and many of these default options are suspicious if not downright harmful. My recommendation is to start by turning off all the automatic options and then selectively turning on just the features you need (based in part on what you learn in this book).

• Prevention is different from problem-solving. Some maintenance apps blur the distinction between preventing problems (what this book focuses on) and solving problems. The result is that you might be tempted to waste time performing tasks that are useful for troubleshooting but worthless or even harmful as prevention. (By analogy, taking antibiotics every day in an attempt to prevent bacterial infections is a terrible idea; you may suffer side-effects, kill beneficial bacteria, encourage the growth of antibiotic-resistant strains, and still get sick from other types of bacteria.)

• Some maintenance tasks require a human touch. An app can empty your Trash or rotate your logs on a schedule, but it can’t decide which apps, files, or email messages are important to you, clean your screen, install a surge protector, or do any of numerous other tasks in this book that require thought, purchases, or background information only you could know.

With those qualifications in mind, I want to call your attention to two general-purpose maintenance apps I use frequently myself and feel comfortable recommending. You can use either or both (there’s some overlap in their features). I hasten to reiterate that these utilities are optional, and shouldn’t be used indiscriminately. But they’re nevertheless among the better examples of their respective genres.

CleanMyMac

I was initially suspicious of CleanMyMac (Figure 8). I’d encountered too many maintenance apps that made outrageous claims, deleted things that should have been left alone, or actively created mischief (see Beware MacKeeper, ahead). But I tried it out anyway—after making a good backup, of course—and looked carefully at what it did. To my surprise, it behaved quite responsibly, and was useful enough for me that I started running it regularly. That’s not to say it’s perfect (read on for some caveats), but it’s pretty good.

CleanMyMac does lots of different things, but I think of it primarily as an uninstaller (refer back to Uninstaller Utilities); it does an excellent job of uninstalling apps as well as getting rid of leftover pieces from apps you previously deleted manually. This function is important because even though you could drag all these files to the Trash yourself, finding them (and knowing which files go with which app) can be incredibly difficult.

Among the other tasks CleanMyMac can perform are:

• Clearing some of your caches (see Consider Clearing Certain Caches) and logs

• Managing (letting you enable, disable, or uninstall) system add-ons such as preference panes, plugins, services, and login items

• Clearing cookies, browsing history, and other browser records

• Removing unneeded localizations from apps and from macOS itself

• Deleting superfluous resources from Photos, iTunes, and Mail

• Running the macOS periodic maintenance scripts (see Make Sure Scheduled Maintenance Tasks Run)

• Locating large and old files that you may want to delete or move to another disk

• Rebuilding Spotlight and Mail indexes

• Updating many third-party apps

• Locating and removing certain types of malware

It can also run selected maintenance tasks on a schedule and can warn you about problems such as dangerously low disk space, apps that have hung, and low memory conditions.

If you use CleanMyMac, please keep these recommendations in mind:

• Take the time to look through the CleanMyMac Help so that you understand what each of its options does.

• Although the default Smart Scan is handy because it tells you about many potential problems at once, I think its default recommendations are excessive. In particular, I urge you to be circumspect about clearing caches (see Consider Clearing Certain Caches) and localization resources (see Clean Out Accumulated Cruft). I prefer to scan one category (like System Junk, Mail Attachments, or Large & Old Files) at a time.

• After CleanMyMac scans your Mac, always review its selections carefully (Figure 9) before clicking Clean. (You can do this by clicking Review Details.) If there’s anything you’re unsure about, deselect it.

OnyX

OnyX has been around since the days of Mac OS X 10.2 Jaguar. Over the years, this multipurpose maintenance tool has grown to include an astonishing array of features.

The interface is divided into six primary panes (for categories such as Maintenance, Cleaning, and Automation), and most of these are further subdivided into multiple views that group related functions. For example, Figure 10 shows the Logs view of the Cleaning pane, on which you can delete any or all of seven types of logs with one click.

Besides log deletion, OnyX shares a number of features with CleanMyMac, such as clearing caches, running maintenance scripts, repairing permissions, reindexing Spotlight and Mail, and deleting browser records. However, it also has a number of features not found in CleanMyMac, including clearing font caches (see Consider Clearing Certain Caches), rebuilding certain system caches, and changing hidden preferences.

This last feature has nothing to do with maintenance as such, but it’s quite useful—a simple, graphical way to adjust many settings that would otherwise require a trip to Terminal and entering obscure command-line instructions. Among many other options, you can turn your Mac’s startup chime on or off (for models that support it); change which users appear on the login screen; display hidden Debug menus in Safari, Disk Utility, Reminders, and other apps; change the behavior of the Dock, Notification Center, and the Help viewer; and change the default file format and location for screenshots.

Because OnyX has so many options and is free, I find that it’s handy to have it in my Utilities folder. It makes a nice companion to CleanMyMac; the two apps together handle the majority of maintenance tasks I cover in this book.

Nevertheless, I should warn you that OnyX has a few annoying quirks:

• It prompts you to enter your administrator password every time you launch it, rather than only when performing actions that require administrator privileges.

• OnyX is excessively chatty. By default, it displays various informational items at launch and quit. (To change this, go to OnyX > Preferences > Actions and uncheck everything.)

• In addition to displaying the items noted in the preceding bullet point, OnyX by default asks you to verify the structure of your startup disk at launch, before letting you do anything else. To make it stop, go to OnyX > Preferences > Advanced and choose Don’t Check.

• Although it has a built-in Check for Updates feature (which is disabled by default), it doesn’t update itself automatically, but rather downloads the new version to your desktop (or another location you choose), after which you must install it yourself.

• There’s a completely different version of OnyX for every version of macOS. So, when you upgrade to next year’s version of macOS, last year’s version of OnyX will no longer work and you’ll have to download an entirely new copy.

Although I’m not crazy about some aspects of the user experience, you can’t beat the price or the convenience of having so many tools together in one place.