A curated list of awesome companies that offer their tools and services for free to Open Source and public projects.
Note: While there are many companies that have great free tiers (Slack, for example), this list focuses specifically on organizations that have made an overt commitment to the Open Source community through additional offerings.
requires-approval - Deployment automation.
      requires-approval - Exception tracking and reporting.
      requires-approval non-commercial - Exception
        and uptime monitoring for Ruby.
      requires-approval -
        NuGet, npm, Bower, Maven, and Vsix package hosting.
      requires-approval - Maven, RPM, DEB, PyPi, and RubyGem
        hosting.
      requires-approval - Automated website monitoring.
      requires-approval - DNS monitoring.
      requires-approval - Cron job monitoring.
      requires-approval - Localization management platform.
      requires-approval - Translation management.
      requires-approval - Localization and Translation Software
        Tool.
      requires-approval - Localization management platform.
      requires-approval - Localization platform for translating
        digital content.
      requires-approval - Web-based continuous localization.
      requires-approval - Distributed Git project hosting.
      requires-approval Search as a service API.
      requires-approval -
        API design, development, and documentation platform.
      requires-approval - Productivity tools for teams (Jira,
        Confluence, Bamboo, HipChat).
      requires-approval -
        SSO & token-based authentication.
      requires-approval - Helps you gather user feedback,
        features requests, schedule interview session with users and notify
        customers about feature rollouts.
      requires-approval - Cross-browser testing tool.
      requires-approval - SSL certificates for open source
        projects.
      requires-approval - Collaborative team email inboxes.
      requires-approval non-commercial - Software
        vendor specializing in the creation of intelligent development tools.
      requires-approval - Authentication and SSO Made Simple.
      requires-approval - Mailing lists for distributed teams.
      requires-approval - Fake SMTP testing server.
      requires-approval - Hosting for static sites.
      requires-approval - Automate end-to-end email tests with
        unlimited mailboxes and a GraphQL API.
      requires-approval - API for file uploading & encoding.
      requires-approval -
        Chat for distributed teams.
      Please see the contributor guidelines and code of conduct for details.
requires-approval
      While many companies use the public repositories feature of GitHub,
      Bitbucket, and GitLab to determine the Open Source status of a project,
      there are others who require more verification. These companies have been
      marked with a requires-approval tag, indicating that an
      application process is required to take advantage of their Open Source
      benefits.
    
non-commercial
      Some companies make their products available for open source, but only for
      non-commercial projects. These companies have been marked with a
      non-commercial tag.