Below is a list, by category, of those applications that I consider essential in my workflow. This post will be updated as old apps disappear (which sometimes they do) or new ones are created.  Do you feel that there’s an app missing from this list?  Let me know in the comments!

Audacity– free, cross-platform software for recording and editing audio. Features include the ability to cut, copy or splice sounds together, to record live audio, to change the speed and pitch of a recording, and much more. Excellent app for podcasters.

Boom 2– Boom is a volume booster and equalizer application that really improve the sound of your Mac. Sound is much louder and clearer when using Boom. It works great with iTunes, YouTube, Rdio & Spotify, Netflix and even Skype.

Marked– If you use Markdown, then Marked is a necessity. Marked provides previews of your Markdown files. You can use it with your text editor (I use it with Byword) and it updates the preview each time you save. Other features include collapsable sections, automatic table of contents (really comes in handy when working with log documents), word & character count, viewing MarsEdit posts as you write, as well as several features for coders.

MarsEdit– This app I use daily. MarsEdit is a blog editing tool that allows you to create your posts off-line, edit them and then post them to your blog. What I like is the ability to write posts in rich text or HMTL and it works great with WordPress, Blogger, and Tumblr (the last time I tried, it wasn’t compatible with the latest version of Squarespace – one of the several reasons I dumped Squarespace). Tons of excellent features and fantastic support! This is my all time favorite blog editor.

iThoughts– Professional mind-mapping software for the Mac. They also have an iOS version, which I use all the time. A nice feature is the ability to import maps from & export apps to a variety of applications such as OPML, Mindmanager, Freemind, My Thoughts, Rich Text and more.

MindNode– Another option for mind-mapping – MindNode is more inexpensive than iThoughts but still quite powerful. A favorite of many people. Easy to get up and running right away as it’s quite intuitive.

Scrapple– Brought to you by the folks atScrivener, Scrapple is a freeform text editor that allows you to make connections between your ideas.

Billings Pro– Powerful time tracking and Invoice generating app. Great for folks who need to keep track of their time & expenses and then bill accordingly. You can invoice clients on the spot and choose to bill for your time, use a flat rate, by project or by quantity. Multi-user & multi-device support. Nice reporting features as well.

Due– Another one of my favorites apps. Due is a super-fast reminders app that provides a central place for them – without having to clutter up your calendar. Many great features in this application including reusable timers, repetitive errands, easy reschedule, persistent reminders with snooze (my favorite feature!) and even the ability to send reminders to your friends.

Excel– Microsoft’s flagship spreadsheet application. Many people prefer it over Apple’s Pages. If you’re a spreadsheet power-user, this is the app for you.Filemaker Pro– Many people who come to Mac from Windows ask me about an equivalent to Microsoft Access. This is it. Filemaker Pro is a relational database system that you can use for your personal stuff as well as for business. There is a bit of a learning curve but once you get the hang of it, you’ll discover that it’s a quite powerful application.

Freshbooks– If you are looking to move your accounting online, you might want to give Freshbooks a look. Great reporting & invoicing features and it integrates with a variety of providers such as PayPal, Stripe, Authorize.net, and MailChimp. Pricing starts at $19.95 a month with a free 30-day trial.

Numbers– Apple’s spreadsheet application. Not quite as feature rich as Excel, but still a worthy contender.

Office Time– I use this app daily. It’s an excellent time-tracking/expense tracking app for the Mac and iOS. Includes iCal sync, summary graphs, ability to easily and quickly change project and categories and built-in invoicing.

Quickbooks– A popular accounting solution for small businesses. You can use their desktop software (which I personally, was never a fan of) or use their Online version. I’ve been usingQuickbooks Onlinefor over 2 years now and have been pleased.

Quicken– Personal Finance and Money Management Software. Until I began my businesses, I used Quicken for many years. Now I track everything inQuickbooks.

Soulver– It’s part calculator and part spreadsheet, that allows you to work with numbers the way you think them. I started out with theiOS versionand became hooked immediately. Features include currency conversions, instant totals, use words alongside your numbers, link lines together, easily edit numbers, advanced mathematical functions and more. You can even save your work and continue later. This has replaced all of my calculator applications.

DiskTools Pro– DiskTools Pro is a utility for the Mac that allows you to schedule when to perform important tasks such as file defragmentation, backup and bad sector repair. With DiskTools Pro you can also create bootable backups, analyze drive capacity, monitor your CPU and much more. A great app to have in your toolbox.

DiskWarrior– Another excellent application to have in your toolbox. DiskWarrior helps you to recover your files and repair your hard drive. This has saved my butt a time or two.

OmniDiskSweeper– OmniDiskSweeper displays the files on your drive, in descending order by size, and lets you decide what to do with them. A nice app to get an overview of what’s taking up your drive space.

Box– Cloud-based file storage and backup. Your first 10 gig is free. Note: Does not support Package files.

Backblaze– Backblaze is an automatic online backup solution that seamlessly uploads your files to the cloud in the background. Can include external drives in backup, a new addition to the company’s services. All for only $5 a month.

Crashplan– CrashPlan backup software provides a seamless way to to back up and store your personal, business and enterprise data securely – offsite, onsite and online in the Cloud. Their family plan is an excellent value. This has been my backup solution for several years now and have had no difficulties at all with it.

DevonThink– A excellent document storage solution that makes document retrieval and exporting easy. Supports a variety of different formats, both for exporting and importing.

Dropbox– No doubt, Dropbox is the leading cloud-based sync and storage service out there. I’ve been with them since they started and couldn’t be more pleased. There are better priced alternatives however.

Evernote– Evernote is one of the most popular note taking apps, allowing you to easily collect and find data. You can create text, photo and audio notes, clip Web pages (including text, links, and images) and organize all of your notes in stacks. I use it to store research, interesting articles that I come across on the Web, various lists and tidbits of information that I want to store for future use.

FileChute– FileChute is a handy utility for sending large files to others. Drag a file and drop it on FileChute. FileChute generates a web link for retrieving the file all in one step. Simply drag the generated link into your email and you’re set to go.

Google Drive– Inexpensive cloud-based file storage provided by Google. Your first 15 gig is free and you can share across Google Drive, Gmail, and Google+ Photos.Name Mangler– Excellent batch file naming utility – includes many options for renaming your files. Super fast!

Onedrive– Microsoft’s cloud-based file storage solution and integrates well with Microsoft Office (formerly called Skydrive). Your first 15 gig is free.

Pathfinder– A Finder alternative that allows you to easily and effortlessly manage your files. Includes such features as dual-pane copy, drop stack, web browser tabs and bookmarks, text & image editing and much more.

Acorn– Acorn is a popular image editing program for the Mac which many people prefer over Photoshop. I personally have not used the application but many folks love it and claim that it’s more than powerful enough for most people’s needs.

Adobe Photoshop– Adobe’s powerhouse photo editing application. Although Photoshop CC (the latest version of Photoshop) now requires a monthly subscription,Photoshop CS 6(the previous version) is still available for sale.

Adobe Photoshop Lightroom– Professional photo editing and management application. If you were an Apple Aperture user, you might want to give Lightroom a look, given that Apple is no longer supporting Aperture.

FX Photo Studio Pro– FX Photo Studio Pro is a photo editing application that offers high quality photo filters and effects, powerful editing tools and stylish photo frames.Picasa– Google’sFreesolution for organizing, editing, and sharing your photos. Integrates with Google+.

Pixelmator– A more affordable alternative to Photoshop, Adobe’s powerhouse photo editing application. I’ll admit – I’ve never worked with Pixelmator (I’m a Photoshop user) but I’ve read nothing but glowing reviews. If Photoshop is overkill for you, Pixelmator might be worth a look.

Skitch– A handy and popular text annotation/markup application that uses shapes and sketches to get your idea across. Owned byEvernote, the app Skitch is free.

Anki– Anki is an intelligent, spaced repetition flashcard program that makes remembering and learning things easy. I use it to help me learn Spanish and I love it.

Audiobook Builder– Audiobook Builder makes it easy to convert your audio CDs & audio files into audiobook format. Once completed, it will automatically import your new audiobook into iTunes.

Comic Life– Okay, maybe Comic Life isn’t anessentialapp, but it is a fun one! With ComicLife you can turn your photos into a comic. You can torture your social media friends by turning your vacation pictures into exciting comic books.

MacGourmet Deluxe– A well-known recipe manager that allows you to import recipes from your favorite food websites or add them in manually.

Paprika Recipe Manager– Paprika recipe manager is another food management application that has quickly become my favorite. Import recipes from your favorite food websites and generate a shopping list that is saved in the Reminders app. If you enjoy cooking, then you’ll love this app.

Kindle App– You don’t need to own a Kindle device to enjoy Kindle books from Amazon. With the free Kindle reading apps, you can buy a Kindle book once, and read it on your Mac or iOS device.

AirMail– An alternative to the Apple’s Mail app. AirMail displays your mail in a unified inbox and supports Google, iCloud, IMAP, POP3, and Exchange. Lots of features in this app, causing it to quickly become the favorite of many people. Apple Mail – Apple’s e-mail client (also known as Mail.app) that comes bundled with OS X.

Chrome– Google’s Web browser. It’s fast and free. Many folks prefer it over Safari. I flip back and forth between Safari and Chrome. Of course, some people preferFirefoxover either of them.

Cyberduck– Free FTP, SFTP, WebDAV, S3 & OpenStack Swift browser for Mac and Windows. This is also one of the few applications that you can use to upload files to Rackspace Cloud. Use it to connect to your Amazon S3 account, Google Cloud Storage, Rackspace, WebDav account and more. Support for bucket versioning and Multi-Factor Authentication. You can also import bookmarks from third party applications. Donationware.

Forklift– ForkLift is a powerful and versatile file manager that includes a fast FTP client. Also connect to SFTP, WebDav, S3, SMB, AFP and NIS. If I’m not using Pathfinder, I’m using Forklift. You can also sync folders (great way to quickly backup a folder to a drive), edit files remotely, browse archives (zip, RAR, gz and tar), create & use synclets and much more. This also has become my most used FTP client.

MailPlane– If you use Gmail, then MailPlane might be for you. It’s a desktop application with Gmail’s familiar interface, including Google Calendar. It allows multiple accounts and integrates nicely with OS X.

Postbox– An excellent alternative to Apple’sMail.app, Postbox has such features as conversation view, powerful tagging, Gmail label support, Gmail keyboard shortcuts, Quick Reply, built-in To-Dos and much more. You can even drag files for your Dropbox folder to send them as links. I reviewed PostBoxHERE.

RapidWeaver– Powerful Web design software for the Mac that includes stunning templates to get you started. Build blogs, Web pages or photo galleries. Nice integration with Google Analytics and GoSquared.

Reeder 2– An excellent RSS reader now available on the Mac. Supports Feedbin, Feedly, Feed Wrangler, FeedHQ, NewsBlur, The Old Reader, Inforeader, Minimal Reader, BazQux Reader, Fever and Readability. Safari – Apple’s own Web browser. Comes bundled with OS X.

SkypeNow owned by Microsoft, Skype allows you to make video and voice calls to anyone else on Skype over your data connections. Also offers instant messaging, file sharing and Calls to mobiles and landlines worldwide at low rates.

Transmit– OK, I’ll admit that I’ve never tried Transmit as Forklift, CyberDuck and YummyFTP currently meet all my needs. But this is a favorite app of many people so I figured I’d mention it. You might want to give it a look as it includes many excellent features.

Yummy FTP– Another great easy-to-use, yet powerful FTP + SFTP + FTPS file transfer client. What I like is its remote file editing capabilities, among it’s other great features. This is my go-to app if I ever need to change permissions (chmod) on remote files.

Apple Music– Apple Music is a digital music streaming service that combines the power of human curation with technology. I gave their 3-month trial a go and I loved the service. Definitely worth a gander.

Pandora– Pandora is a personalized streaming music application that plays music according to your tastes. Discover new music and enjoy old favorites. Free, but subscription removes ads.

Radium– Radium is awesome Internet Radio with which you can listen to stations from around the world. Sits out of the way in your menu bar.

Spotify– Another digital music streaming service (perhaps the most popular) with which you can play specific songs from your favorite artists. Now free on mobile, tablet and computer.

Keynote– Apple’s powerful presentation application, originally part of the iWork suite but now available separately along with Pages and Numbers.

PowerPoint– Microsoft’s ubiquitous presentation app. Part of theMicrosoft Office suitefor Mac.

Adobe Acrobat Professional– The most powerful and feature-rich PDF editor/creation tool out there. Convert files to PDF, export PDF files, create electronic forms, edit PDFs and much more.

Alfred– Alfred is popular application launcher that I have not personally use but which many people recommend and swear by. Use it launch Applications & find files or quickly search the Web.

AppCleaner– A handy utility to ensure that when you delete an application that it’scompletelydeleted – including Library, Application Support and cache files.

BusyCal– A powerful alternative to the built-in Calendar app on OS X. Includes customizable calendar views, integrated Info Panel for quickly viewing and editing events,integrated To Dos that display in the calendar(from your Reminders app) and carry-forward until completed.

Cobook– Is an integrated replacement for your Mac’s Contacts app. With Cobook, you can sync your OS X/iCloud contacts with Google contacts, as well as Twitter, Facebook, Foursquare, Instagram, LinkedIn, and more.

CoffeeBreak– A countdown timer that darken your screen when your times about up and then counts down during your break. Great if you use thePomodoro technique. One of my regularly used apps.

Fantastical– A slick alternative to OS X’s calendar application that sits in your menu bar. Open Fantastical with a single click or keystroke, type in the details of your event and press Return. Easy to use.

Keyboard Maestro– Keyboard Maestro is an application with which you create macros to automate tasks on your Mac. The possibilities are endless. One of my favorite – and essential – apps.

LaunchBar– LaunchBar is an application launcher (and much more) that provides access to user’s applications and files, by entering short abbreviations of the searched item’s name. Access applications, documents, bookmarks, contacts, use clipboard history, browse & control iTunes, search the Web, perform calculations, create calendar events, create reminders, and more. I use this app dozens of times every day.

NvAlt– NvAlt is a fork of Notational Velocity that includes additional features. What it is, is a plain text editor with super-fast searching and easy note organization. Matches to title or content display immediately as you begin typing. I have hundreds of note snippets that I store in NvAlt, knowing that I can retrieve what I’m looking for in seconds.

OmniFocus– A powerful project and management application by the OmniGroup. I reviewed OmniFocusHERE.

OmniOutliner– a flexible app for creating, collecting and organizing information in outline format. Includes multiple columns, checkboxes and styles.

PDFPen– Another fine offering from Smile software, PDF Pen is an all-purpose PDF editor for the Mac. You can edit PDF text, correct typos, add signatures, text or images to PDFs, fill out forms and export to Microsoft Word. If you edit, revise or otherwise work with PDFs, then this might be an excellent app to add to your toolbox.

Simplenote– A clean and easy-to-use note taking app. Sync your notes online and among your iOS Devices. Features include quick searching, automatic backup, and tagging. Sync with NvAlt and Dropbox.

TextExpander– This is another one of those apps that I wouldn’t be able to do without as it makes my workflow so much easier. TextExpander saves you time & keystrokes, expanding custom keyboard shortcuts into frequently-used text and pictures. This is the first app I install on a new Mac – I feel lost without it.

ToDoIst– Todoist is flexible yet powerful online task management app and to-do list with a clean, minimalist interface. I did a review of Todoist on the blog. You can read my review of itHERE.

Readkit– Read all of your Instapaper, Pocket, Readability, Feedly, Fever, NewsBlur, Feed Wrangler and Feedbin articles & blogs in once place. Also supports built-in RSS so you can enter in your feeds manually.

Reeder 2– My favorite RSS reader for iOS is now available for the Mac as well! Read all your favorite blogs with Reeder 2’s clean interface. Supports all major feed-syncing services.

Tweetbot– My favorite full-featured Twitter client for both iOS and Mac. Supports multiple timelines, multiple accounts, and muting users. You can also mute hashtags or specific keywords.

TweetDeck– Now owned by Twitter, TweetDeck allows you to organize & build custom timelines, keep track of lists, searches, activity and more—all in one interface. Great for viewing multiple Twitter streams on one window.

1Password– Another of my most-used and essential applications. Use 1Password to easily store and generate secure, random passwords that are accessible anywhere from Dropbox or iCloud. It’s strongest feature IMHO is that it provides easy access to your 1Password data directly from Safari, Chrome, Firefox and Opera and if you visit sites often, you can automatically sign in with a single click.

Bartender– Bartender lets you organize your menu bar apps, by hiding them, rearranging them, or moving them to Bartender’s Bar. It’s nice to have a tidy menu bar.

BetterZip– Create archives in most common formats. Although OS X comes with built-in zip archiving support, the additional features of this app make it worth a look, such as password protecting archives and previewing files in an archive with QuickLook.

Carbon Copy Cloner– With Carbon Copy Cloner that can clone your entire drive quickly and easily as well as create regular backups. I wrote about Carbon Copy Cloner inthis post.

CheatSheet– Hold down the ⌘ key and get a list all keyboard shortcuts for the active application. Great for learning shortcuts! I wrote about thisHERE.

Cocktail– Cocktail is an excellent Mac utility that allows you to manage various aspects of your Mac from an easy to use interface. Includes Tweaks and Maintenance tasks.

DaisyDisk– DaisyDisk analyzes your disk usage and shows you graphically which files and folders are taking up the most space on your drive.

Default Folder X– Probably one my most-used apps. Default Folder X allows you to open folders with a keyboard shortcut as well as many other features. I wrote about Default Folder X inthis blog post.

Fluid– Fluid lets you create a Mac desktop application out of any website or web application. Great for those web apps that don’t have a desktop sibling.

Forklift– Forklift is an advanced file manager and FTP + SFTP + Amazon S3 + WEBDav client for Mac OS X all in one application. This feature-rich program is one of my all time favorites and has all but replaced the Finder for me.

Hands Off!– Protect your privacy by monitoring outgoing connections.

Hazel– Another one of my favorite apps! Hazel watches whatever folders you tell it to and then automatically organizes your files according to the rules you create.

Little Snitch– This applicationsnitcheson any application that is trying to access the Internet in order to phone home. Another excellent privacy-protecting app.

Moom– An essential app if you spend a lot of time moving and resizing windows. Why not just let Moom do it for you?

Onyx– OnyX is a multi-use utility for OS X that allows you to verify the startup disk and the structure of its System files, to run various system maintenance tasks, configure the hidden parameters of the Finder, Dock, Spotlight, as well as some of Apple’s own applications, delete caches, and more.

Send to Kindle– Drag and drop one or more documents on to the Send to Kindle icon in your Dock and the items are sent to your Kindle account for storage, allowing you to reading them on your iOS devices or on your Kindle.

SuperDuper– In addition to Carbon Copy Cloner, there is SuperDuper, another excellent application that clones your hard drive. Check it out and decide which one you prefer.

Ttimer– A timer application used for timing tea – but its flexibility allows for a plethora of uses.

WhatSize– WhatSize measures the size of your hard drive and allows you to sort, filter, and refine the results. The files and folders are automatically sorted by size with the biggest sizes first, allowing you to see which files & folders are hogging your disk space.

Handbrake– HandBrake is a free tool for converting video from nearly any format to a selection of widely supported outputs. Includes built-in device presets to help you get started quickly. Other features include chapter markers, title/chapter selection, subtitles, video filters and more.

Mac DVD Ripper ProMac DVDRipper Pro allows you to copy DVDs to your Mac as well as compress each movie on the fly – making them viewable on video iPod, iPod Touch, iPhone, iPad, & Apple TV.

Plex– I love, love, love this app! Plex organizes all of your personal media (movies, TV shows & music) so you can enjoy it no matter what device you are on. It’s video & audio streaming made super easy. Runs on Windows, Mac, Linux, iOS, Android & Windows 8.1 phone and connects to Amazon Fire, TV, Roku and Google TV. Ability to create your own music and video playlists and import your existing iTunes playlists.

ScreenFlow– The best (in my humble opinion) high quality screen recording and editing software for your Mac. Use ScreenFlow to create instructional videos, web casts and more. Another one of my favorite applications.

VLC Media Player– VLC is a free open source multimedia player and framework that plays most multimedia files as well as DVDs, Audio CDs, and more. It plays pretty much anything so if Quicktime Play or DVD Play won’t play it, maybe VLC will. There’s an iOS version as well.

Bean– One of my favorite easy-to-use word processors…and it’sfree! I wrote a blog post about Bean that you can viewHERE.

BBEdit– BBEdit is the leading professional HTML and text editor that is specifically tailored to Web authors and software developers. A developer favorite.

Byword– If you write in MarkDown then Byword is for you! My favorite Markdown text editor. It’s fast, efficient and you can export to HTML (as well as to many other formats) right from the application.

DayOne– I’ve tried many journaling apps over the years and this one is by far the best one I’ve come across. It has a clean uncluttered interface, supports multimarkdown and syncs between your Mac and iOS devices. You can also insert images, password protect your entries and include information such as location, weather and music playing in your entries. This app will transform your journaling.

Dragon Dictate– With Dragon Dictate, you can transcribe, edit and write text all by voice. This application gets better all the time. Another one of my favorites and highly-used apps. Why type when you can talk?

IAWriter– an excellent text editor for distraction-free writing. I like its focus mode, which highlights in on the active line you’re working on.

MacJournal– Powerful journaling application with tons of features: multiple journals, upload journals to blog, extensive media browser and much more.

Mariner Write– Although I tend to rarely use word processors these days, many people I know love and are faithful to Mariner Write, a powerful app without the bloated extras.

Microsoft Word– Considered essential by many, I could not leave out Microsoft’s power word processor – Microsoft Word. Need lots of features? Then this app’s for you.

Pages– Apple’s own word processor. If I need to do word processing, Pages is my go-to app.

Scrivener– Okay, hands down, this is my favorite all-time application! It’s a powerful and flexible content-generation tool for writers: novelists, bloggers, technical writers, attorneys, playwrights – just about anyone who creates long documents. The majority of my work is done in Scrivener.

Sublime Text– Another awesome text editor especially aimed at those who write in code or markup (although you can easily use it for prose).

Text Wrangler– TextWrangler is thelittle brotherto BBEdit (mentioned above). TextWrangler itself is a full-featured editor including Web authoring & software development tools.

WriteRoom– A full-screen text editor for those who like writing without distractions.

Did I forget something?  Let me know in the comments!