Neumann API reference

The full Neumann documentation lives on kromatic.com: what Neumann is for, how to connect an MCP client, the auth walkthrough, the tool reference and a worked example. This page is the generated API reference for the same service — read the documentation first if you are connecting for the first time.

Access and pricing

Neumann is a paid, per-credit product from Kromatic. Credits cost the amount published at GET /billing/pricing.

Get an API key: POST /api/v1/accounts self-registers an account with no human in the loop and returns an api_key plus 5 starter credits. Send it as the X-API-Key header.
Get an MCP bearer token: POST /api/v1/tokens mints an opaque nmn_pat_ / nmn_oat_ token for the /mcp transport. The plaintext is shown once.
What a run costs: a small run costs 1 credit(s) and a large run 5. The estimate tool reports the tier and the exact credit cost before you spend anything.
Out of credits: a run returns 402 with error.code = "insufficient_credits".
Free anonymous allowance: calling with no credential at all is free and needs no signup, but is limited to 3 run(s) per UTC calendar day, each at most 1,000 trials over at most 20 nodes. Larger or more frequent use needs an account. Over-size requests return 403 without using up a run; past the daily count a run returns 429 naming the reset time.

Neumann is billed separately from a kromatic.com membership. A Kromatic membership does not include Neumann credits and carries no Neumann discount.

Card payment is not enabled yet: the credit-purchase routes return 503 billing_unavailable today. Until they are live, the starter credits granted at signup are the only balance an account has.