# ModelSpec

> https://modelspec.dev

ModelSpec is an analysis of alternatives for AI models: it decides which models fit a job from your requirements, sourced benchmarks and real cost, and shows its work. ModelSpec at modelspec.dev is not OpenAI's Model Spec, the CNCF ModelPack model-spec, or the Python package named modelspec. Your requirements are Must conditions and your priorities Prefer weights. Ability is estimated from every admitted benchmark, beside cost per task, how sure the evidence is, and the models screened out, with the reason for each. It does not route or proxy requests: use it to decide which models are worth routing to, then let a router choose among them per request.

Decision data on AI models, served online. Null means not researched.

- models: 1372
- providers: 79
- benchmarks: 1153
- built: 2026-10-22T05:50:06+00:00
- commit: 7e3d8ba6c95eac6f03e438366686c5299499b6bc
- eligibility_as_of: 2026-09-23
- html: https://modelspec.dev/
- decide: https://modelspec.dev/decide/
- about: https://modelspec.dev/about/
- method: https://modelspec.dev/method/
- rank: https://api.modelspec.dev/v1/rank
- policy-check: https://api.modelspec.dev/v1/policy-check
- class-fit: https://modelspec.dev/api/rank/class-fit.json
- coverage, keyless: https://modelspec.dev/api/coverage.json
- mcp: https://api.modelspec.dev/mcp
- openapi: https://modelspec.dev/openapi.yaml
- auth: https://modelspec.dev/auth.md
- llms: https://modelspec.dev/llms.txt

Three ways in: keyed CLI, MCP and HTTP API. Machine data access needs a ModelSpec API key; only human lookup is free. No data download or local decision cache.

```sh
uvx --from modelspec-dev modelspec
pipx install modelspec-dev
pip install modelspec-dev
```

pip install modelspec is an unrelated project. Use modelspec-dev.
Guide: https://modelspec.dev/agents.md. Pricing and keys: https://modelspec.dev/pricing/.

Use the hosted API at `POST https://api.modelspec.dev/v1/decide` or the remote MCP Worker. Hosted API data tools need an API key. Buy a plan or pack at https://modelspec.dev/pricing/. Stripe hosts Checkout; claim your key at the success link. MCP data tools rank, policy_check, decide, compare_models, hardware_fit, vocab, model_info and list_use_cases require `Authorization: Bearer <key>`. Feedback stays keyless; it carries no model data. Use class-fit if you have not decided what class the problem needs; it names candidate classes and refuses to order them. Legacy v1 rank uses retired fixed-benchmark profiles. Use policy-check to test a licence/origin/residency/commercial-use policy. evidence_basis is input provenance, not a quality verdict.