API Reference

Base URL: https://api.nexotao.com. Authentication via API key — see Authentication.

Endpoints

Method	Path	Function
`GET`	`/models`	Public pricing catalog for the site (no key)
`GET`	`/v1/models`	OpenAI-format model list (requires key) — used by n8n etc.
`GET`	`/v1/models/{id}`	Single model detail, OpenAI format (requires key)
`POST`	`/v1/chat/completions`	Chat, OpenAI format (DeepSeek and Claude)
`POST`	`/v1/responses`	OpenAI Responses format — supports streaming; used by Codex CLI
`POST`	`/v1/messages`	Chat, Anthropic format (Claude models)

Response headers

Header	Meaning
`X-Request-Id`	The request id for tracking. Present on every response, including streaming
`X-Cost-Rp`	The actual cost of the request in Rupiah. Non-streaming responses only
`X-Error-Code`	The `code` value from the error body. Error responses only

On streaming (SSE) responses X-Cost-Rp is not sent — the cost isn’t known when headers are flushed. Read the final figure from GET /usage/{request_id}; see Billing & Pricing.

Error codes

Status	Meaning	Action
`400`	Invalid request	Check the body/parameters
`401`	Invalid or revoked API key	Create / use an active key
`402`	Insufficient balance	Top up your Rupiah balance
`413`	Request body too large	Compact the history or start a new session
`429`	Too many requests	Retry with backoff
`502`	Upstream unavailable	Retry with backoff

Error body shape

Every error returns JSON in the same shape:

{
  "error": "invalid api key",
  "code": "auth.api_key_invalid",
  "type": "api_key_invalid",
  "request_id": "8997bda3-65c4-45c3-ab38-c909f905fc4d",
  "retryable": false
}

Field	Type	Meaning
`error`	string	Human-readable message. The wording can change — don’t branch on it
`code`	string	Stable dotted identifier, e.g. `auth.api_key_invalid`. Branch on this
`type`	string	The segment after the last dot of `code` (e.g. `api_key_invalid`). Legacy client compatibility
`request_id`	string	The request id, identical to the `X-Request-Id` header. Include it when reporting an issue
`retryable`	bool	`true` when retrying the same request is sensible (e.g. rate limits, upstream errors)
`hint`	string	Optional. Present on some errors only, with actionable guidance

Branch your code on code (or the X-Error-Code header), never on error. The full code catalogue is on Error Codes.

GET /models

Returns the list of active models along with sell prices (no internal cost data). Used by the live pricing tables on the Billing and Models & Pricing pages.

curl https://api.nexotao.com/models

Each item contains: model, display_name, tier, provider, supports_vision, modality, and the *_micro price fields (micro-rupiah; 1 Rp = 1,000,000 micro).

Billing & Pricing Errors & Debugging