Portkey alternatives
The highest-scoring alternative to Portkey is Vellum at 88/100 on the AgentReady, against 63/100 for Portkey.
All scored in LLM Observability & Evals.
What Vellum does that Portkey does not
Vellum passes llms-full.txt / full agent docs, structured api reference, openapi / spec quality, request examples provided, response examples provided, errors and status codes documented, programmatic credential creation, fast time to first request, copyable quickstart, structured, predictable output, machine-readable errors, retry behavior documented, and Portkey fails them. That is the whole of the gap between the two scores, so if none of those matter to your agent the ranking above overstates the difference.
Why people look for an alternative
Portkey fails llms-full.txt / full agent docs, structured api reference, openapi / spec quality, request examples provided, response examples provided, errors and status codes documented, programmatic credential creation, fast time to first request, copyable quickstart, structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable, agent compatibility verified. Each one is a place an unattended run stops, which is usually what sends someone looking in the first place.
Where Portkey loses the points
| Pillar | Portkey | What it measures |
|---|---|---|
| Discover | 93 | Can an agent find it at all: sitemap, robots, structured data. |
| Understand | 38 | Is there a spec, an llms.txt, a machine-readable description. |
| Adopt | 80 | Signup, keys, SDKs, and whether a human has to be involved. |
| Operate | 39 | Rate-limit headers, errors, status, and behaviour under load. |
Portkey is weakest on understand at 38/100. Without a spec an agent has to guess at endpoints, and it guesses wrong. If that is the part your agent depends on, take the ranking above seriously; if it is not, Portkey may still be the right pick.
What an agent runs into with Portkey
These are the findings from the last audit on 2026-08-22. Each one is a place unattended software stops, which is the practical reason to look at the list above.
- Publish an OpenAPI spec so agents can generate a client.
- Flesh out the OpenAPI: paths, schemas, and descriptions.
- Document error responses as an enum in your OpenAPI.
- Let agents create API keys programmatically.
- Return X-RateLimit / Retry-After headers so agents pace themselves.
- Publish an AGENTS.md or llms-full.txt with full agent context.
- Add request examples to your API reference.
- Add response examples to your API reference.
What this category actually supports
Across the 13 products scored in LLM Observability & Evals, trace / evaluate llm apps is offered by 77%.
An agent can get this list directly: resolve("alternative to Portkey") over the MCP server, or GET /v1/categories/llm-observability.