Statistically speaking, the odds of having a problem with your Mac increase with continuous use and age. Sometimes the problem may not get noticed for years. But if and when it does, the consequences can be devastating.

Erratic Mac behavior may be due to failing physical components, software malfunctions, errors in the filesystem, and more. You can minimize or solve the problems with a few tools and a maintenance regime.

Let's look at the best Mac diagnostic, maintenance, and system tools to detect and fix common macOS problems.

1. Disk Utility

disk utility app

Disk Utility is a built-in tool for inspecting file systems, mounting or unmounting volumes, formatting drives, and fixing other problems.

During startup, your Mac performs a consistency check of the partition scheme and volume directory structure. If any problems arise, you can select the volume or disk you want to repair, then click First Aid.

If your Mac won’t boot, you should open Disk Utility through Recovery Mode. To do this, press and hold the Power button for an M1 Macs or press and hold Cmd + R while booting up for older Macs with an Intel processor. Keep holding the buttons until you see the Options window or a macOS Recovery screen. Then, proceed with the repair.

You may need to create an image file of your startup disk. To do so, connect an external disk, then open Disk Utility and choose File > New Image > Image from Folder. From the dialog box that appears, select Macintosh HD and proceed.

If Disk Utility repair options don’t work, boot into single-user mode and use "fsck" to fix your drive.

2. Apple Diagnostic Test

apple diagnostic test

Apple Diagnostics is another tool that checks your hardware components for any issues. The comprehensive range of diagnostic tests included in this tool helps you identify subtle hardware defects or distinguish a hardware issue from a software one. Apple's diagnostic tests come in customized versions for every Mac model.

You can run this tool from an external boot drive (such as a USB drive or DVD), an invisible Recovery HD volume installed as part of macOS, or over the internet. To start a diagnostic test, shut down your Mac and disconnect all the external devices except the Ethernet cable, keyboard, or monitor.

For M1 Macs, press and hold the Power button as your Mac boots. Then, release it when you see the Options window. Press Cmd + D on your keyboard to start the test.

In Intel Macs, press and hold the D key while your Mac boots. When testing is over, check out the reference codes from diagnostic test results on the Apple website for more detailed information.

3. OnyX

maintenance feature built into onyx app

OnyX is a diagnostic, maintenance, and system utility app for Mac. The interface is divided into four primary panes—Maintenance, Utilities, Files, and Parameters. Each category is further divided into multiple views that group related functions.

You can verify the file system structure and rebuild the Spotlight, Mail, LaunchServices databases in case you’re having search-related issues. OnyX also has a comprehensive maintenance feature built into the app. You can clean system, applications, and font-based caches. Although, remember that periodic cleaning might slow down or harm your Mac.

The app lets you access hidden apps like Network Utility, Wireless Diagnostics, and Directory Utility. It even provides a graphical way to adjust settings that would usually require Terminal. For example, you can configure Finder, Dock, window effects, file formats, locations of screenshots, and much more with OnyX.

Download: OnyX (Free)

4. MemTest86

memtest86 for Mac

RAM is one of the last internal components Apple allowed Mac owners to customize—particularly on older MacBooks and iMac. Sometimes the RAM can lead to issues where user-installed memory is faulty. Application hangs, triple beep on startup, crashes, and system freeze are all symptoms of bad memory.

MemTest86 is a comprehensive memory testing software that uses 13 different sophisticated algorithms and test patterns to check your RAM. Download the MemTest86 package, unzip it and look for the memtest86-usb.img file.

Now create a bootable USB drive using the image, insert your USB drive, and hold the Option key when your Mac boots. Then, follow the prompts to use MemTest 86.

Depending on what's causing the memory errors, try the following options—increase the RAM voltage levels, decrease the CPU voltage levels, change the default or conservative RAM timings, or update BIOS to fix incompatibility issues.

Download: MemTest86 (Free, premium version available)

5. Malwarebytes

malwarebytes app for Mac

Although Apple has built numerous protections—like XProtect, Gatekeeper, Malware Removal Tool, and System Integrity Protection—your Mac is still susceptible to malware.

If you’re experiencing high CPU usage not caused by any app, if your search engine got changed, or if you see notifications to install questionable system utilities, there could be malware on your Mac.

Malwarebytes helps you detect and remove malware, adware, viruses, and other potentially unwanted programs.

Click the Scan button and wait for a few moments to let it complete. If it detects any threat, check the boxes next to the item and click Quarantine. After quarantining threats, it shows you the scan summary.

The free version lacks scheduled scan and real-time protection, but it offers ample protection for most users.

Download: Malwarebytes (Free, premium version available)

6. KnockKnock

knockknock app for Mac

Whether it’s a malicious browser extension that injects ads into search results or malware that aims to steal your data, the goal of any malicious app is to run in the background for every macOS session. “Persistence” is a technique by which malware ensures that it’ll get executed by the OS on startup.

KnockKnock works on this principle of persistence. It lists all the installed apps and their components in a neat interface.

Click Scan and pay close attention to the Launch Items section, which lists all the daemons and agents. Each row gives detailed information like signature status, application path, and antivirus scan results.

Download: KnockKnock (Free)

7. EtreCheck

etrecheck scan ongoing for Mac

There could be many day-to-day problems with your Mac. It could be an application hogging resources, intermittent beach ball, failing hard disk, or maybe malware infections. Etrecheck is a utility that runs over a dozen diagnostic scans to give you a comprehensive report on the state of your Mac.

It includes hardware information, software compatibility issues (32-bit apps or unsigned components), status of launchagents or daemons and whether they’re running or not, security status (including information on XProtect, MRT, and Gatekeeper), user login items, top processes, and more.

EtreCheck works in tandem with Apple Support Communities to help users with limited technical knowledge solve their Mac problems. It is my tool of choice, and I use it every month to check for any issues.

Download: EtreCheck ($18, free trial available)

8. OmniDiskSweeper

omnidisksweeper app for Mac

macOS requires a certain amount of breathing room for temporary files, virtual memory, application support data, and more. When your disk is nearly full, your Mac performance may deteriorate sharply. Symptoms like application hangs, crashes, and even kernel panics are quite common.

OmniDiskSweeper is a utility to find and delete big or useless files. Select the startup drive and click Sweep Selected Drive. Within a few moments, the folders and files arrange themselves in a column view (similar to in Finder) from largest to smallest. Find the one that takes up the most disk space, select it, and click Trash.

Download: OmniDiskSweeper (Free)

9. TinkerTool System 6

tinkertool system app for Mac

TinkerTool System 6 is a collection of system utilities that let you perform advanced administrative tasks not available to you through the conventional user interface. If you’re facing weird issues related to apps, caches, Time Machine backups, or file permission issues, then TinkerTool can be of great help.

Rebuild the shared cache of the dynamic link editor, launch services, clear the memory cache of directory services, and recreate shared folder in case you accidentally delete them. You can clear the cache of a particular app causing problems, font cache of the user or OS, icon cache, and more.

TinkerTool lets you perform complex file operations not available in any app. You can check the file alias or Finder attributes to aid Spotlight search. You can clean old log or crash reports, core dumps, and orphaned files. You can even check file and folder permissions and troubleshoot them.

TinkerTool has a built-in application uninstaller to completely remove apps from your Mac. You can reset an app’s privacy settings so it can't access critical data or perform security checks for authenticity.

You can also create an emergency installation media in case something goes wrong with your Mac and fails to boot properly.

TinkerTool can perform a check on Time Machine backup snapshots, it can create a detailed log when backup goes wrong, or it can assign a Time Machine backup from an old to newer Mac.

Download: TinkerTool System 6 ($14, free trial available)

Don’t Forget Your Boot Modes

Your Mac uses various boot modes for all kinds of troubleshooting functions. For example, if you want to boot into Recovery Mode, boot from a USB drive, or test your hardware using Apple diagnostic tools, you’ll need to use the right combination of startup keys.

If this interests you, check out the list of Mac boot modes for fixing a wide range of problems that can affect your Mac.