Readers comparing API development and testing tools need a way to separate the highest-scoring options from a larger field. This September 2026 section uses the supplied ToolVitals records and their ToolVitals, health, shipping, openness, license, and GitHub-star fields.
The list includes open/source-visible tools only. Tools are ordered by ToolVitals score descending; when composite scores are equal, health and shipping decide the order. GitHub stars are context only and do not determine rank.
Rankings
| Rank | Tool | Openness | License | Health | Shipping | GitHub Stars | Score | Status |
|---|---|---|---|---|---|---|---|---|
| 1 | LiteLLM | OSI-approved OSS | MIT | 98 | 99 | 58226 | 98 | 🟢 Excellent |
| 2 | Bifrost | OSI-approved OSS | Apache-2.0 | 98 | 98 | 7841 | 98 | 🟢 Excellent |
| 3 | AxonHub | OSI-approved OSS | Apache-2.0 | 98 | 97 | 5175 | 97 | 🟢 Excellent |
| 4 | Bruno | OSI-approved OSS | MIT | 97 | 97 | 46802 | 97 | 🟢 Excellent |
| 5 | Kuadrant MCP Gateway | OSI-approved OSS | Apache-2.0 | 97 | 97 | 98 | 97 | 🟢 Excellent |
| 6 | Ministack | OSI-approved OSS | MIT | 97 | 97 | 4532 | 97 | 🟢 Excellent |
| 7 | Scalar | OSI-approved OSS | MIT | 97 | 97 | 16073 | 97 | 🟢 Excellent |
| 8 | new-api | OSI-approved OSS | AGPL-3.0 | 97 | 97 | 47428 | 97 | 🟢 Excellent |
| 9 | MCP Context Forge | OSI-approved OSS | Apache-2.0 | 97 | 96 | 4428 | 97 | 🟢 Excellent |
| 10 | OpenAPI Generator | OSI-approved OSS | Apache-2.0 | 97 | 96 | 26730 | 97 | 🟢 Excellent |
| 11 | Traefik | OSI-approved OSS | MIT | 97 | 96 | 64763 | 97 | 🟢 Excellent |
| 12 | Apache APISIX | OSI-approved OSS | Apache-2.0 | 97 | 96 | 17092 | 96 | 🟢 Excellent |
| 13 | Insomnia | OSI-approved OSS | Apache-2.0 | 97 | 96 | 39999 | 96 | 🟢 Excellent |
| 14 | Keploy | OSI-approved OSS | Apache-2.0 | 97 | 96 | 18442 | 96 | 🟢 Excellent |
| 15 | WunderGraph | OSI-approved OSS | Apache-2.0 | 97 | 96 | 1263 | 96 | 🟢 Excellent |
| 16 | Higress | OSI-approved OSS | Apache-2.0 | 97 | 95 | 9305 | 96 | 🟢 Excellent |
| 17 | Unkey | OSI-approved OSS | AGPL-3.0 | 96 | 97 | 5432 | 96 | 🟢 Excellent |
| 18 | Specmatic | OSI-approved OSS | MIT | 96 | 96 | 396 | 96 | 🟢 Excellent |
| 19 | kgateway | OSI-approved OSS | Apache-2.0 | 96 | 95 | 5684 | 96 | 🟢 Excellent |
| 20 | Inference Gateway | OSI-approved OSS | Apache-2.0 | 96 | 95 | 211 | 95 | 🟢 Excellent |
| 21 | PostgREST | OSI-approved OSS | MIT | 95 | 95 | 27643 | 95 | 🟢 Excellent |
| 22 | FakeCloud | OSI-approved OSS | AGPL-3.0 | 94 | 97 | 542 | 95 | 🟢 Excellent |
| 23 | Karate | OSI-approved OSS | MIT | 94 | 96 | 8945 | 95 | 🟢 Excellent |
| 24 | testcontainers-go | OSI-approved OSS | MIT | 95 | 93 | 4971 | 94 | 🟢 Excellent |
| 25 | Membrane API Gateway | OSI-approved OSS | Apache-2.0 | 94 | 94 | 641 | 94 | 🟢 Excellent |
| 26 | Tyk | OSI-approved OSS | AGPL-3.0 | 94 | 90 | 10817 | 93 | 🟢 Excellent |
| 27 | Gravitee | OSI-approved OSS | Apache-2.0 | 93 | 88 | 449 | 91 | 🟢 Excellent |
| 28 | Hurl | OSI-approved OSS | Apache-2.0 | 92 | 89 | 19190 | 91 | 🟢 Excellent |
| 29 | Hoppscotch | OSI-approved OSS | MIT | 92 | 88 | 80230 | 91 | 🟢 Excellent |
| 30 | HttpArena | OSI-approved OSS | MIT | 92 | 87 | 109 | 90 | 🟢 Excellent |
| 31 | Microcks | OSI-approved OSS | Apache-2.0 | 92 | 87 | 2036 | 90 | 🟢 Excellent |
| 32 | OkHttp | OSI-approved OSS | Apache-2.0 | 91 | 85 | 47061 | 89 | 🟢 Excellent |
| 33 | mitmproxy | OSI-approved OSS | MIT | 90 | 85 | 44941 | 88 | 🟢 Excellent |
| 34 | API Dash | OSI-approved OSS | Apache-2.0 | 89 | 83 | 2900 | 87 | 🟢 Excellent |
| 35 | Kumo | OSI-approved OSS | MIT | 89 | 83 | 1470 | 86 | 🟢 Excellent |
| 36 | MCP Assert | OSI-approved OSS | MIT | 85 | 89 | 24 | 86 | 🟢 Excellent |
| 37 | Emissary | OSI-approved OSS | Apache-2.0 | 86 | 83 | 4519 | 85 | 🟢 Excellent |
| 38 | GhostPour | OSI-approved OSS | MIT | 84 | 87 | 4 | 85 | 🟢 Excellent |
| 39 | Tailcall | OSI-approved OSS | Apache-2.0 | 85 | 79 | 1443 | 83 | 🟢 Excellent |
| 40 | Hasura | OSI-approved OSS | Apache-2.0 | 83 | 79 | 32115 | 81 | 🟢 Excellent |
| 41 | Requesto | OSI-approved OSS | MIT | 80 | 81 | 6 | 80 | 🟢 Excellent |
| 42 | KrakenD | OSI-approved OSS | Apache-2.0 | 82 | 71 | 2675 | 77 | 🟢 Good |
| 43 | Yasumu | OSI-approved OSS | AGPL-3.0 | 73 | 74 | 46 | 74 | 🟢 Good |
| 44 | tRPC | OSI-approved OSS | MIT | 76 | 60 | 40588 | 70 | 🟢 Good |
| 45 | pREST | OSI-approved OSS | MIT | 74 | 59 | 4614 | 68 | 🟢 Good |
| 46 | Webhookx | OSI-approved OSS | Apache-2.0 | 68 | 66 | 297 | 67 | 🟢 Good |
| 47 | Apache JMeter | OSI-approved OSS | Apache-2.0 | 68 | 48 | 9528 | 60 | 🟢 Good |
| 48 | Kong | OSI-approved OSS | Apache-2.0 | 68 | 45 | 44092 | 59 | 🟡 Fair |
| 49 | digiRunner | OSI-approved OSS | Apache-2.0 | 63 | 52 | 306 | 59 | 🟡 Fair |
| 50 | Fusio | OSI-approved OSS | Apache-2.0 | 63 | 51 | 2114 | 58 | 🟡 Fair |
Top 3 Highlights
LiteLLM ranks first with a ToolVitals score of 98, a health score of 98, and a shipping score of 99. Its listed scope combines a Python SDK and Proxy Server (AI Gateway) for calling 100+ LLM APIs in OpenAI or native format, with cost tracking, guardrails, loadbalancing, and logging. ToolVitals labels it OSI-approved OSS and MIT.
Bifrost ranks second with a ToolVitals score of 98, a health score of 98, and a shipping score of 98. Its listed capabilities include an adaptive load balancer, cluster mode, guardrails, support for 1000+ models, and a claimed <100 µs overhead at 5k RPS. ToolVitals labels it OSI-approved OSS and Apache-2.0.
AxonHub ranks third with a ToolVitals score of 97, a health score of 98, and a shipping score of 97. Its listed focus is an AI Gateway that lets users call 100+ LLMs through any SDK, with built-in failover, load balancing, cost control, and end-to-end tracing. ToolVitals labels it OSI-approved OSS and Apache-2.0.
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