Developers and Open Source authors now have a massive amount of services offering free tiers, but it can be hard to find them all in order to make informed decisions.
The scope of this particular list is limited to things infrastructure developers (System Administrator, DevOps Practitioners, etc.) are likely to find useful. We love all the free services out there, but it would be good to keep it on topic. It's a bit of a grey line at times so this is a bit opinionated; do not be offended if I do not accept your contribution.
You can help by sending Pull Requests to add more services. Once I have a good set of links in this README file, I'll look into a better layout for the information and links (help with that is appreciated too).
* [cloud.google.com](https://cloud.google.com/tools/cloud-repositories/) — Free private Git repositories hosted on Google Cloud Platform. Supports syncing with existing GitHub and Bitbucket repos. Free Beta for up to 500 MB of storage
* [scinote.net](http://scinote.net) — Scientific data management and team collaboration. One Team with unlimited number of users, backup and 1 GB storage space
* [seafile.com](https://www.seafile.com/) — Private or cloud storage, file sharing, sync, discussions. Private version is full. Cloud version has just 1 GB
* [yammer.com](https://www.yammer.com/) — Private social network standalone or for MS Office 365. Free with a bit less admin tools and users management features
* [wunderlist.com](https://www.wunderlist.com/) — Share your lists and work collaboratively on projects with your colleagues, free on iPhone, iPad, Mac, Android, Windows and the web
* [filehero.io](https://filehero.io/) — Make it easy to access your company's file storage from a corporate download page. Free for 5 concurrent downloads
* [wistia.com](http://wistia.com/) — Video hosting with viewer analytics, HD video delivery and marketing tools to help understand your visitors, 25 videos and Wistia branded player
* [codacy.com](https://codacy.com/) — Automated code reviews for PHP, Python, Ruby, Java, JavaScript, Scala, CSS and CoffeeScript, free for Open Source
* [browserling.com](https://www.browserling.com/) — Live interactive cross-browser testing, free only 3 minutes sessions with MS IE 9 under Vista at 1024 x 768 resolution
* [loadfocus.com](https://loadfocus.com/) — Load and speed tests for websites, mobile apps and APIs, monitoring,... Free 5 tests/month, 120 clients/test, 1 monitor, 1 location
* [versioneye.com](https://www.versioneye.com/) — Monitor your source code and notify about outdated dependencies. Free for Open Source and public repos
* [beanstalkapp.com](http://beanstalkapp.com/) — A complete workflow to write, review and deploy code), free account for 1 user and 1 repository with 100 MB of storage
* [testanywhere.co](https://testanywhere.co/) — Automatic test website or web app continuously and catch bugs in the early stages, free 1,000 tests/month
* [blamewarrior.com](https://blamewarrior.com/) — Tool to automatically assign reviewers for new pull requests and track statistics of review process, free for Open Source
* [gerrithub.io](https://review.gerrithub.io/) — Gerrit code review for GitHub repositories for free
* [reviewable.io](https://reviewable.io/) — Code review for GitHub repositories, free for public or personal repos
* [sonarqube.com](https://sonarqube.com) — Automated source code analysis for Java, JavaScript, C/C++, C#, VB.NET, PHP, Objective-C, Swift, Python, Groovy and even more languages, free for Open Source
* [gridlastic.com](https://www.gridlastic.com/) — Selenium Grid testing with free plan up to 4 simultaneous selenium nodes/10 grid starts/4,000 test minutes/month
* [everystep-automation.com](https://www.everystep-automation.com/) — Records and replays all steps made in a web browser and creates scripts,... free with fewer options
* [Applitools.com](https://applitools.com/) — smart visual validation for web, native mobile and desktop apps. Integrates with almost all automation solutions (like Selenium and Karma) and remote runners (Sauce Labs, Browser Stack). free for open source. A free tier for a single user with limited checkpoints per week.
* [threatconnect.com](https://www.threatconnect.com) — Threat intelligence: It is designed for individual researchers, analysts and organizations who are starting to learn about cyber threat intelligence. Free up to 3 Users
* [snyk.io](https://snyk.io) — Snyk found and reported several vulnerabilities in the package.Limited to 1 private project (unlimited for open source projects)
* [opswatgears.com](https://www.opswatgears.com/) — Security Monitoring of computers, devices, applications, configurations,... Free 25 users and 30 days history
* [bitninja.io](https://bitninja.io/) — Botnet protection through a blacklist, free plan only reports limited information on each attack
* [onelogin.com](https://www.onelogin.com/) — Identity as a Service (IDaaS), Single Sign-On Identity Provider, Cloud SSO IdP, 3 company apps and 5 personal apps, unlimited users
* [logintc.com](https://www.logintc.com/) — Two-factor authentication (2FA) by push notifications, free for 10 users, VPN, Websites and SSH
* [appdynamics.com](https://www.appdynamics.com/) — Free for 24 hours metrics, application performance management agents limited to one Java, one .NET, one PHP and one Node.js
* [apimetrics.io](http://apimetrics.io/) — Automated API Performance Monitoring, Testing and Analytics. Free Plan, manually make API calls and Run from their West Coast servers
* [algolia.com](https://www.algolia.com/) — Hosted search-as-you-type (instant). Free hacker plan up to 10,000 documents and 100,000 operations. Bigger free plans available for community/Open Source projects
* [swiftype.com](https://swiftype.com/) — Hosted search solution (API and crawler). Free for a single search engine with up to 1,000 documents. Free upgrade to premium level for Open Source
* [mailtrap.io](https://mailtrap.io/) — Fake SMTP server for development, free plan with 1 inbox, 50 messages, no team member, 2 emails/second, no forward rules
* [developers.google.com](https://developers.google.com/speed/libraries/) — The Google Hosted Libraries is a content distribution network for the most popular, Open Source JavaScript libraries
* [asp.net](https://www.asp.net/ajax/cdn/) — The Microsoft Ajax CDN hosts popular third party JavaScript libraries such as jQuery and enables you to easily add them to your Web application
* [firebase.com](https://www.firebase.com/) — Build real-time apps, free plan has 100 max. connections, 10 GB data transfer, 1 GB data storage, 1 GB hosting storage and 10 GB hosting transfer
* [bluemix.net](https://console.ng.bluemix.net/) — IBM PaaS with a monthly free allowance
* [outsystems.com](http://www.outsystems.com/) — Enterprise web development PaaS for on-premise or cloud, free "personal environment" offering allows for unlimited code and up to 1 GB database
* [platform.telerik.com](https://platform.telerik.com/) — Build and deploy mobile applications using JavaScript. Free plan has 100 MB data storage, 1 GB file storage, 5 GB bandwidth, 1 million push notifications for BaaS offering, 100 active devices for analytics
* [scn.sap.com](https://scn.sap.com/docs/DOC-56411) — The in-memory Platform-as-a-Service offering from SAP. Free developer accounts come with 1 GB structured, 1 GB unstructured, 1 GB of Git data and allow you to run HTML5, Java and HANA XS apps
* [mendix.com](https://www.mendix.com/) — Rapid Application Development for Enterprises, unlimited number of free sandbox environments supporting 10 users, 100 MB of files and 100 MB database storage each
* [zeit.co/now](https://zeit.co/now) — Managed platform for Node.js deployments, featuring dynamic real-time scaling. Includes 20 free deploys/month limited to 1 GB storage and 1 GB bandwidth for OSS projects (source files are exposed on a public URL)
* [sandstorm.io](https://sandstorm.io/) — Sandstorm is an open source operating system for personal and private clouds. Free plan offers 200 MB storage and 5 grains free
* [apigee.com](http://docs.apigee.com/api-baas) — Unlimited trial includes NoSQL data store with 25 GB of storage, user and permission management, geolocation, 10 million push notifications/month, remote configuration, beta and A/B split testing, APM, fully API driven. Accessible and manageable via UI, SDK and API
* [bip.io](https://bip.io/) — A web-automation platform for easily connecting web services. Fully open GPLv3 to power the backend of your Open Source project. Commercial OEM License available
* [blockspring.com](https://www.blockspring.com/) — Cloud functions. Free for 5 million runs/month
* [kinvey.com](http://www.kinvey.com/) — Mobile backend, starter plan has unlimited requests/second, with 2 GB of data storage, as well as push notifications for up 5 million unique recipients. Enterprise application support
* [getstream.io](https://getstream.io/) — Build scalable news feeds and activity streams in a few hours instead of weeks, free for 3 million feed updates/month
* [stackstorm.com](https://stackstorm.com/) — Event-driven automation for apps, services and workflows, free without flow, access control, LDAP,...
* [simperium.com](https://simperium.com/) — Move data everywhere instantly and automatically, multi-platform, unlimited sending and storage of structured data, max. 2,500 users/month
* [stamplay.com](https://stamplay.com/) — Connect services together with a visual interface. 50,000 API calls, 100 GB data transfer and 1 GB storage for free
* [closeheat.com](https://closeheat.com/) — Development Environment in the Cloud for Static Websites with Free Hosting and GitHub integration. 1 free website with custom domain support
* [serverpilot.io](https://serverpilot.io/) ServerPilot, and we'll install everything you need to host PHP apps like WordPress. Unlimited servers, 1 SSH/SFTP user
* [acquia.com](https://www.acquia.com/) — Hosting for Drupal sites. Free tier for developers. Free development tools (such as Acquia Dev Desktop) also available
* [contentful.com](https://www.contentful.com/) — Content as a Service. Content management and delivery APIs in the cloud. 3 users, 3 repositories and 100,000 API requests/month for free
* [tilda.cc](https://tilda.cc/) — One site, 50 pages, 50 MB storage, only the main pre-defined blocks among 170+ available, no fonts, no favicon and no custom domain
* [airtable.com](https://airtable.com/) — Looks like a spreadsheet, but it's a relational database, unlimited bases, 1,200 rows/base and 1,000 API requests/month
* [fieldbook.com](https://fieldbook.com/) — Fieldbook lets anyone create a simple tracking database, as easily as a spreadsheet. Automatic API. Unlimited free sheets, share with unlimited users
* [cloudamqp.com](https://www.cloudamqp.com/) — RabbitMQ as a Service. Little Lemur plan: max 1 million messages/month, max 20 concurrent connections, max 100 queues, max 10,000 queued messages, multiple nodes in different AZ's
* [hub.jazz.net](https://hub.jazz.net/) — IBM Bluemix's project management services. Free for public projects, free for up to 3 users for private projects
* [leankit.com](http://leankit.com/) — Kanban board, that visualizes your workflow. Free up to 10 users
* [visualstudio.com](https://www.visualstudio.com//products/what-is-visual-studio-online-vs) — Unlimited free private code repositories; Tracks bugs, work items, feedback and more
* [targetprocess.com](http://targetprocess.com/) — Visual project management, from Kanban and Scrum to almost any operational process. Free for unlimited users, up to 1,000 data entities {[more details](http://www.targetprocess.com/pricing/)}
* [overv.io](https://overv.io/) — Agile project management for teams who love GitHub
* [taskulu.com](https://taskulu.com/) — Role based project management. Free up to 5 users. Integration with GitHub/Trello/Dropbox/Google Drive
* [jetbrains.com](https://www.jetbrains.com/youtrack/buy/#edition=incloud) — search based on time tracking, attachments on Agile Board, and many other improvements. 10 users 5 GB free
* [cloudinary.com](http://cloudinary.com/) — Image upload, powerful manipulations, storage and delivery for sites and apps, with libraries for Ruby, Python, Java, PHP, Objective-C and more. Perpetual free tier includes 7,500 images/month, 2 GB storage, 5 GB bandwidth
* [transloadit.com](https://transloadit.com/) — Handles file uploads and encoding of video, audio, images, documents. Free for Open Source and other do-gooders. Commercial applications get 1 GB free for test driving
* [podio.com](https://podio.com/) — You can use Podio with a team of up to five people and try out the features of the Basic Plan, except users management
* [shrinkray.io](https://shrinkray.io/) — Free image optimization of GitHub repos
* [embed.ly](http://embed.ly/) — Provides APIs for embedding media in a webpage, responsive image scaling, extracting elements from a webpage. Free for up to 5,000 URLs/month at 15 requests/second
* [otixo.com](http://otixo.com/) — Encrypt, share, copy and move all your cloud storage files from one place. Basic plan provides unlimited files transfer with 250 MB max. file size and allows 5 encrypted files
* [packagecloud.io](https://packagecloud.io/) — Hosted Package Repositories for YUM, APT, RubyGem and PyPI. Limited free plans, open source plans available via request
* [geocoder.opencagedata.com](https://geocoder.opencagedata.com/) — Geocoding API that aggregates OpenStreetMap and other open geo sources. 2,500 free queries/day
* [latlon.io](https://latlon.io/) — Geocoding API + school districts, census geography divisons and other address based data. 2,500 free requests/month
* [mapbox.com](https://mapbox.com/) — Maps, geospatial services and SDKs for displaying map data
* [c9.io](https://c9.io/) — IDE in a browser. Incorporates an Ubuntu virtual machine and in-browser terminal access. Integrates with GitHub and BitBucket, but also adds SFTP and generic Git access
* [koding.com](http://www.koding.com/) — Cloud-based development environment. You have a Ubuntu OS machine
* [codeanywhere.com](https://codeanywhere.com/) — Full IDE in the browser and mobile apps. Access FTP, SFTP, Dropbox, Google Drive, GitHub and BitBucket. Hosted virtual machines with terminal access. Collaboration features like share links, live editing, permissions and version tracking
* [codenvy.com](https://codenvy.com/) — IDE and automated developer workspaces in a browser, collaborative, Git/SVN integration, build and run your app in customizable Docker-based runners (free tier includes: 4 GB RAM, always-on machines, ability to run multiple machines simultaneously), pre-integrated deploy to Google Apps
* [visualstudio.com](http://visualstudio.com/community) — Fully-featured IDE with thousands of extensions, cross-platform app development (Microsoft extensions available for download for iOS and Android), desktop, web and cloud development, multi-language support (C#, C++, JavaScript, Python, PHP and more)
* [code.visualstudio.com](http://code.visualstudio.com/) — Build and debug modern web and cloud applications. Code is free, Open Source and available on your favorite platform, Linux, Mac OSX and Windows
* [cloud.sagemath.com](https://cloud.sagemath.com/) — Collaborative mathematics-oriented IDE in a browser, with support for Python, LaTeX, IPython Notebooks, etc
* [wakatime.com](https://wakatime.com/) — Quantified self metrics about your coding activity, using text editor plugins, limited plan for free
* [apiary.io](https://apiary.io/) — Collaborative design API with instant API mock and generated documentation (Free for unlimited API blueprints and unlimited user with one admin account and hosted documentation)
* [mockable.io](https://www.mockable.io/) — Mockable is a simple configurable service to mock out RESTful API or SOAP web-services. This online service allows you to quickly define REST API or SOAP endpoints and have them return JSON or XML data
* [jetbrains.com](https://jetbrains.com/products.html) — Productivity tools, IDEs and deploy tools. Free license for students, teachers, Open Source and user groups
* [ironSource atom](http://www.ironsrc.com/data-flow-management/) — Atom Data Flow Management is a data pipeline solution, 10 million monthly events free
* [cognalys.com](https://cognalys.com/) — Freemium mobile number verification through an innovative and reliable method than using SMS gateway. Free 10 tries and 15 verifications/day
* [numverify.com](https://numverify.com/) — Global phone number validation and lookup JSON API. 250 API requests/month
* [braintreepayments.com](https://braintreepayments.com/) — Credit Card, Paypal, Venmo, Bitcoin, Apple Pay,... integration. Single and Recurrent Payments. First USD 50,000 free
* [taxratesapi.avalara.com](http://taxratesapi.avalara.com/) — Get the right sales tax rates to charge for the close to 10,000 sales tax jurisdictions in the USA. Free REST API. Registration required
* [Docker Cloud](https://cloud.docker.com) — Manages the deployments of Docker containers to your (separate) cloud environment with one free repository
* [canister.io](https://canister.io/) — 20 free private repositories for developers, 30 free private repositories for teams to build and store Docker images
* [instadiff.com](http://www.instadiff.com/) — Compare website versions with highlighted changes before you deploy, free for 100 pages/month
* [fullcontact.com](https://fullcontact.com/developer/pricing/) — Help your users know more about their contacts by adding social profile into your app. 500 free Person API matches/month
* [screenshotmachine.com](https://screenshotmachine.com/) — Capture 100 snapshots/month, png, gif and jpg, including full-length captures, not only home page
* [dreamfactory.com](http://dreamfactory.com/) — Open source REST API backend for mobile, web, and IoT applications. Hook up any SQL/NoSQL database, file storage system, or external service and it instantly creates a comprehensive REST API platform with live documentation, user management,...
* [monkeylearn.com](http://monkeylearn.com/) — Text analysis with machine learning, free 100,000 queries/month
* [mashape.com](https://www.mashape.com/) — API Marketplace and powerful tools for private and public APIs. With the free tier, some features are limited such as monitoring, alerting and support
* [havenondemand.com](https://www.havenondemand.com) — APIs for machine learning
* [restlet.com](http://restlet.com/products/apispark/) — APISpark enables any API, application or data owner to become an API provider in minutes via an intuitive browser interface
* [scrapinghub.com](http://scrapinghub.com) — Data scraping with visual interface and plugins. Free plan includes unlimited scraping on a shared server