Choosing an API development or testing tool can mean sorting through gateways, clients, emulators, contract-testing suites, and related infrastructure while separating current project health from popularity. For August 2026, the supplied ToolVitals data provides each ranked tool’s ToolVitals score, health score, shipping score, openness label, license label, and GitHub-star count.
The list is limited to open/source-visible tools and ordered by ToolVitals score descending; where composite scores are equal, health and shipping break the tie. GitHub stars are context only, not a ranking input, so popularity does not override the ToolVitals ordering.
Rankings
| Rank | Tool | Openness | License | Health | Shipping | GitHub Stars | Score | Status |
|---|---|---|---|---|---|---|---|---|
| 1 | AxonHub | OSI-approved OSS | Apache-2.0 | 100 | 100 | 4925 | 100 | 🟢 Excellent |
| 2 | Bifrost | OSI-approved OSS | Apache-2.0 | 100 | 100 | 7166 | 100 | 🟢 Excellent |
| 3 | Bruno | OSI-approved OSS | MIT | 100 | 100 | 46225 | 100 | 🟢 Excellent |
| 4 | Insomnia | OSI-approved OSS | Apache-2.0 | 100 | 100 | 39932 | 100 | 🟢 Excellent |
| 5 | Kuadrant MCP Gateway | OSI-approved OSS | Apache-2.0 | 100 | 100 | 95 | 100 | 🟢 Excellent |
| 6 | Kumo | OSI-approved OSS | MIT | 100 | 100 | 1439 | 100 | 🟢 Excellent |
| 7 | LiteLLM | OSI-approved OSS | MIT | 100 | 100 | 55968 | 100 | 🟢 Excellent |
| 8 | MCP Context Forge | OSI-approved OSS | Apache-2.0 | 100 | 100 | 4286 | 100 | 🟢 Excellent |
| 9 | Ministack | OSI-approved OSS | MIT | 100 | 100 | 3980 | 100 | 🟢 Excellent |
| 10 | Scalar | OSI-approved OSS | MIT | 100 | 100 | 15876 | 100 | 🟢 Excellent |
| 11 | Specmatic | OSI-approved OSS | MIT | 100 | 100 | 393 | 100 | 🟢 Excellent |
| 12 | Traefik | OSI-approved OSS | MIT | 100 | 100 | 64360 | 100 | 🟢 Excellent |
| 13 | WunderGraph | OSI-approved OSS | Apache-2.0 | 100 | 100 | 1247 | 100 | 🟢 Excellent |
| 14 | kgateway | OSI-approved OSS | Apache-2.0 | 100 | 100 | 5655 | 100 | 🟢 Excellent |
| 15 | new-api | OSI-approved OSS | AGPL-3.0 | 100 | 100 | 44728 | 100 | 🟢 Excellent |
| 16 | AI Gateway | OSI-approved OSS | Apache-2.0 | 98 | 99 | 92 | 98 | 🟢 Excellent |
| 17 | FakeCloud | OSI-approved OSS | AGPL-3.0 | 98 | 99 | 514 | 98 | 🟢 Excellent |
| 18 | Inference Gateway | OSI-approved OSS | Apache-2.0 | 98 | 99 | 230 | 98 | 🟢 Excellent |
| 19 | PostgREST | OSI-approved OSS | MIT | 98 | 99 | 27501 | 98 | 🟢 Excellent |
| 20 | Unkey | OSI-approved OSS | AGPL-3.0 | 98 | 99 | 5413 | 98 | 🟢 Excellent |
| 21 | testcontainers-go | OSI-approved OSS | MIT | 98 | 97 | 4943 | 98 | 🟢 Excellent |
| 22 | Apache APISIX | OSI-approved OSS | Apache-2.0 | 98 | 96 | 16971 | 97 | 🟢 Excellent |
| 23 | OpenAPI Generator | OSI-approved OSS | Apache-2.0 | 98 | 96 | 26657 | 97 | 🟢 Excellent |
| 24 | Karate | OSI-approved OSS | MIT | 96 | 95 | 8916 | 96 | 🟢 Excellent |
| 25 | Keploy | OSI-approved OSS | Apache-2.0 | 96 | 93 | 18380 | 95 | 🟢 Excellent |
| 26 | Membrane API Gateway | OSI-approved OSS | Apache-2.0 | 96 | 92 | 630 | 94 | 🟢 Excellent |
| 27 | Gravitee | OSI-approved OSS | Apache-2.0 | 95 | 90 | 443 | 93 | 🟢 Excellent |
| 28 | HttpArena | OSI-approved OSS | MIT | 95 | 90 | 91 | 93 | 🟢 Excellent |
| 29 | Higress | OSI-approved OSS | Apache-2.0 | 94 | 89 | 9055 | 92 | 🟢 Excellent |
| 30 | MCP Assert | OSI-approved OSS | MIT | 90 | 94 | 23 | 92 | 🟢 Excellent |
| 31 | Hurl | OSI-approved OSS | Apache-2.0 | 94 | 87 | 19133 | 91 | 🟢 Excellent |
| 32 | Hasura | OSI-approved OSS | Apache-2.0 | 96 | 82 | 32081 | 90 | 🟢 Excellent |
| 33 | Hoppscotch | OSI-approved OSS | MIT | 96 | 82 | 80000 | 90 | 🟢 Excellent |
| 34 | Tyk | OSI-approved OSS | AGPL-3.0 | 94 | 83 | 10789 | 90 | 🟢 Excellent |
| 35 | Previa | OSI-approved OSS | MIT | 86 | 92 | 3 | 88 | 🟢 Excellent |
| 36 | GhostPour | OSI-approved OSS | MIT | 85 | 89 | 4 | 87 | 🟢 Excellent |
| 37 | mitmproxy | OSI-approved OSS | MIT | 93 | 75 | 44622 | 86 | 🟢 Excellent |
| 38 | Stoa | OSI-approved OSS | Apache-2.0 | 84 | 88 | 2 | 86 | 🟢 Excellent |
| 39 | Microcks | OSI-approved OSS | Apache-2.0 | 89 | 79 | 2011 | 85 | 🟢 Excellent |
| 40 | NyaProxy | OSI-approved OSS | MIT | 77 | 83 | 976 | 79 | 🟢 Good |
| 41 | API Dash | OSI-approved OSS | Apache-2.0 | 82 | 68 | 2873 | 76 | 🟢 Good |
| 42 | pREST | OSI-approved OSS | MIT | 82 | 68 | 4610 | 76 | 🟢 Good |
| 43 | KrakenD | OSI-approved OSS | Apache-2.0 | 80 | 64 | 2661 | 74 | 🟢 Good |
| 44 | Requesto | OSI-approved OSS | MIT | 76 | 71 | 5 | 74 | 🟢 Good |
| 45 | Tailcall | OSI-approved OSS | Apache-2.0 | 78 | 64 | 1442 | 72 | 🟢 Good |
| 46 | Kong | OSI-approved OSS | Apache-2.0 | 76 | 55 | 43951 | 68 | 🟢 Good |
| 47 | Requestly | OSI-approved OSS | AGPL-3.0 | 76 | 55 | 6747 | 68 | 🟢 Good |
| 48 | Yasumu | OSI-approved OSS | AGPL-3.0 | 66 | 68 | 46 | 67 | 🟢 Good |
| 49 | Lura | OSI-approved OSS | Apache-2.0 | 73 | 51 | 6786 | 64 | 🟢 Good |
| 50 | Fusio | OSI-approved OSS | Apache-2.0 | 69 | 57 | 2113 | 64 | 🟢 Good |
Top 3 Highlights
AxonHub ranks first with a ToolVitals score of 100 and supplied health and shipping scores of 100 each. Its first-party description presents it as an AI gateway that lets any SDK call more than 100 LLMs, with built-in failover, load balancing, cost control, and end-to-end tracing. AxonHub is labeled OSI-approved OSS and Apache-2.0.
Bifrost ranks second with a ToolVitals score of 100 and supplied health and shipping scores of 100 each. Its first-party project description lists adaptive load balancing, cluster mode, guardrails, support for more than 1,000 models, and reported overhead below 100 µs at 5k RPS. Bifrost is labeled OSI-approved OSS and Apache-2.0.
Bruno ranks third with a ToolVitals score of 100 and supplied health and shipping scores of 100 each. Its first-party description identifies it as an open-source IDE for exploring and testing APIs and a lightweight alternative to Postman and Insomnia. Bruno is labeled OSI-approved OSS and MIT.
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