API reference · contract snapshot

HTTP API

This static contract snapshot describes documented routes and is not generated from deployed handlers. the OpenAPI document at /openapi.json is the machine-readable reference.

POST/v1/systemone

Submit exactly one text question and receive its typed answer. More than one question returns non-retryable HTTP 400 request_limit_exceeded; the service never silently drops or splits questions. Request fields: model, state, questions.

Headers: bearer API key, Content-Type: application/json, optional S1-Region: eu|global, optional Idempotency-Key.

POST/v1/multimodal

Submit one typed question plus validated PNG, JPEG or WebP image data where the selected model supports images. More than one question returns non-retryable HTTP 400 request_limit_exceeded. Current candidate limits and validation status are listed in the source summary; image input is coming soon.

GET/v1/models

Return model cards, supported question types and modalities, prices, and tier availability from the live registry.

GET/models JSON compatibility alias

Alias on the API host for the legacy Jev Router JSON catalogue. Check the response against your client before relying on it.

GET/v1/usage

Account-scoped usage receipts expose integer charge_nanos values and currency. The route requires a signed-in dashboard session; its exact authentication and host setup are not published. This static page does not call the account API.

GET/v1/balance

Account balance uses integer available_nanos, reserved_nanos, credited_total_nanos and currency. The route requires a signed-in dashboard session; its exact authentication and host setup are not published. This static page does not call the account API.

Candidate request limits

The current candidate allows state up to 16 KiB, request bodies up to 6 MiB, and up to 4,096 actual input tokens after model tokenization. Choice-option limits vary by profile. Image input is coming soon. See all candidate bounds, measured input maxima and validation status.

Approved rates are listed on the pricing page. Successful billable requests include exact charge units in S1-Charge-Nanos and S1-Currency. Charges use integer nanos with no per-request rounding.

Answer types

Typed output

Answers preserve the question keys and the question type. The contract requires probabilities for choice and score answers.

Type	Answer field	Meaning
`noul`	`noul`	Probability of true, between 0 and 1.
`choice`	`choice`, `confidence`, `probabilities`	Chosen option ID and distribution over the criteria.
`score`	`score`, `confidence`, `legend`, `probabilities`	Probability-weighted expected rubric level; score may be fractional.

Read the static OpenAPI contract snapshot: OpenAPI 3.1 JSON. Compatibility is limited to the shared state and questions structure. Provider, model IDs, tiers, authentication, billing, limits and metadata are System1 extensions. Byte-for-byte compatibility is not claimed pending an integration test against TypeSafe’s documented schema.