Errors

The error envelope

Errors share one shape. code is -1, message is human-readable, and error repeats the message so the body reads like a normal REST error. Some errors add extra fields that tell you what to do next.

{
  "code": -1,
  "message": "\"input\" is required",
  "error": "\"input\" is required"
}

Status codes

`400 Bad Request`

The request never reached the model. Nothing was billed.

Message	Cause
`Request body must be JSON`	The body could not be parsed.
`Request body must be a JSON object`	The body was valid JSON but not an object.
`"input" is required`	`input` (or `state`) was missing or empty.
`At least one question is required`	`questions` was missing or empty.
`Question "<key>" requires a "prompt" (or "instructions") string`	A question had no prompt.
`Question "<key>" of type "choice" requires a "criteria" object, ...`	A `choice` question had no criteria.
`Question "<key>" of type "score" requires a "criteria" array, ...`	A `score` question had no criteria.
`Question "<key>" has an unsupported type. Use one of: choice, score, noul`	The `type` was not recognised.

`401 Unauthorized`

Message	Cause
`Missing API key. Pass it as "Authorization: Bearer sk-..."`	No bearer token on the request.
`Invalid API key`	The key does not exist, was deleted, or is disabled.

`402 Payment Required`

The account has no usable credits.

{
  "code": -1,
  "message": "Insufficient credits",
  "error": "Insufficient credits",
  "remaining_credits": 0
}

Buy a credit pack to continue. See Limits & credits.

`429 Too Many Requests`

The daily allowance is used up. See Limits & credits for the full rules.

{
  "code": -1,
  "message": "You have reached the daily free limit of 100 decisions. Buy credits to lift it.",
  "error": "You have reached the daily free limit of 100 decisions. Buy credits to lift it.",
  "daily_limit": 100,
  "reset_at": "2026-11-01T09:14:22.000Z",
  "remaining_credits": 812,
  "upgrade_path": "/settings/credits"
}

`500 Internal Server Error`

The service could not complete the call — for example Jev decision failed unexpectedly, or Jev upstream is not configured. Nothing was billed. Retry after a short delay; if it persists, contact support with the request id.

`502 Bad Gateway`

The upstream model rejected the request, or answered in a way the API could not turn into a decision. The message carries the upstream status and body so you can see what the provider said. Nothing was billed.

Handling errors in code

const response = await fetch('https://jevmodel.io/api/v1/decisions', options);
const payload = await response.json();

if (!response.ok) {
  switch (response.status) {
    case 400:
      throw new Error(`Bad request: ${payload.message}`);
    case 401:
      throw new Error('The API key is missing or invalid.');
    case 402:
      throw new Error('Out of credits.');
    case 429:
      throw new Error(`Rate limited until ${payload.reset_at}.`);
    default:
      throw new Error(`Jev API error ${response.status}: ${payload.message}`);
  }
}

Retrying

400, 401, and 402 will not succeed on a retry. Fix the request, the key, or the balance first.
429 succeeds after reset_at.
500 and 502 are worth retrying with exponential backoff. Since a failed call is not billed, a retry costs you nothing beyond the upstream call.

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