head to head · open source
Insomnia vs openapi-generator
Insomnia has 40,021 GitHub stars, 2,365 forks, 874 open issues and last shipped yesterday. openapi-generator has 26,745 stars, 7,674 forks, 5,751 open issues and last shipped yesterday. Insomnia leads on adoption by 50% (40,021 vs 26,745 stars). Insomnia is written in TypeScript under Apache-2.0; openapi-generator is written in Java under Apache-2.0. Insomnia has attracted 6% as many forks as stars, openapi-generator 29%. openapi-generator was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (api, api-client, rest-api), so they are genuine substitutes rather than adjacent tools.
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 | openapi-generator | |
|---|---|---|
| GitHub stars | ★ 40K | ★ 27K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | TypeScript | Java |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 2.4K | ⑂ 7.7K |
| 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 openapi-generator if
- You want the openapi-generator 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 openapi-generator fits your workflow better
About Insomnia
Insomnia is an open source, cross platform API client built with Electron and TypeScript for developing and testing APIs across multiple protocols including REST, GraphQL, WebSockets, SSE, and gRPC. It runs on macOS, Windows, and Linux and is distributed under the Apache 2.0 license. The project serves as a direct open source alternative to Postman, offering similar core functionality without vendor lock in or mandatory cloud usage.
read the full Insomnia overview →
About openapi-generator
OpenAPI Generator is an Apache 2.0 licensed Java tool that generates API client libraries, server stubs, documentation, and configuration automatically from an OpenAPI Specification, and it is built for development teams that keep a machine readable API description and want generated code to stay in step with it.
read the full openapi-generator overview →
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Frequently asked questions
Is Insomnia or openapi-generator more popular?
Insomnia has 40,021 GitHub stars and openapi-generator has 26,745. Insomnia has the larger community by that measure.
Are Insomnia and openapi-generator free?
Both are open source. Insomnia is licensed under Apache-2.0 and openapi-generator under Apache-2.0. Neither carries a licence fee.
What is the difference between Insomnia and openapi-generator?
Insomnia is written in TypeScript and openapi-generator 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 openapi-generator?
Choose Insomnia if you want the larger community (40,021 stars) or its Apache-2.0 licence terms. Choose openapi-generator if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.