head to head · open source
Insomnia vs greenmail
Insomnia has 40,111 GitHub stars, 2,388 forks, 874 open issues and last shipped yesterday. greenmail has 749 stars, 205 forks, 67 open issues and last shipped yesterday. Insomnia leads on adoption by 5,255% (40,111 vs 749 stars). Insomnia is written in TypeScript under Apache-2.0; greenmail is written in Java under Apache-2.0. Insomnia has attracted 6% as many forks as stars, greenmail 27%. greenmail was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Insomnia | greenmail | |
|---|---|---|
| GitHub stars | ★ 40K | ★ 749 |
| License | Apache-2.0 | Apache-2.0 |
| Written in | TypeScript | Java |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 2.4K | ⑂ 205 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Insomnia if
- You weight community size — 40K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick greenmail if
- You want the greenmail feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and greenmail fits your workflow better
About Insomnia
Insomnia API Client Insomnia is an open source, cross platform API client for GraphQL, REST, WebSockets, Server Sent Events (SSE), gRPC and any other HTTP compatible protocol. With Insomnia you can: Debug APIs using the most popular protocols and formats. Design APIs using the native OpenAPI editor and visual preview. Test APIs using native test suites and collection runner. Mock APIs using a cloud or self hosted mocking server. Build CI/CD pipelines using the native Insomnia CLI for linting and testing. Collaborate with others using the many collaboration features. And more including the ability to use 3rd…
read the full Insomnia overview →
About greenmail
GreenMail [ ][docker hub] [GreenMail][greenmail project site] allows developers to test email based applications, services or systems without access to a live mail server. Developers can send, receive, and verify emails by embedding GreenMail in a unit test or running it as a standalone container. GreenMail acts as a virtual (mocking/sandbox) mail server and supports common mail protocols SMTP, IMAP and POP3. [Examples][greenmail examples] [Javadoc][greenmail javadoc] [FAQ][greenmail faq] [Download][greenmail download] [Maven coordinates][maven repository com]: com.icegreen:greenmail:\ The separate GreenMail…
read the full greenmail overview →
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Frequently asked questions
Is Insomnia or greenmail more popular?
Insomnia has 40,111 GitHub stars and greenmail has 749. Insomnia has the larger community by that measure.
Are Insomnia and greenmail free?
Both are open source. Insomnia is licensed under Apache-2.0 and greenmail under Apache-2.0. Neither carries a licence fee.
What is the difference between Insomnia and greenmail?
Insomnia is written in TypeScript and greenmail in Java. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Insomnia or greenmail?
Choose Insomnia if you want the larger community (40,111 stars) or its Apache-2.0 licence terms. Choose greenmail if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.