NeonAPI Docs

POST /v1/chat/completions

Authentication

Use your NeonAPI API key in Authorization: Bearer YOUR_API_KEY. Keep the key in a trusted application environment.

Availability and compatibility

Check the selected model’s protocol, permissions, price and supported parameters before calling. Unsupported parameters may be rejected. Request examples use placeholders.

Request fields

application/json

Field	Type	Required	Constraints	Meaning
`model`	`string`	Yes	—	Exact published model ID.
`messages`	`Message[]`	Yes	—	Ordered conversation messages with role and content.
`temperature`	`number`	No	≥ 0; ≤ 2; default: `1`	Sampling temperature where supported.
`top_p`	`number`	No	≥ 0; ≤ 1; default: `1`	Nucleus sampling probability.
`n`	`integer`	No	≥ 1; default: `1`	Number of generated results; model limits apply.
`stream`	`boolean`	No	default: `false`	Request incremental streaming events.
`stream_options`	`object`	No	—	Stream options, including usage where supported.
`stop`	`string / string[]`	No	—	—
`max_tokens`	`integer`	No	—	Output token limit; model-dependent.
`max_completion_tokens`	`integer`	No	—	Completion token budget for compatible models.
`presence_penalty`	`number`	No	≥ -2; ≤ 2; default: `0`	—
`frequency_penalty`	`number`	No	≥ -2; ≤ 2; default: `0`	—
`logit_bias`	`object`	No	—	—
`user`	`string`	No	—	—
`tools`	`Tool[]`	No	—	Tool definitions supplied by your application.
`tool_choice`	`string / object`	No	—	Control whether/how a tool is selected.
`response_format`	`ResponseFormat`	No	—	Desired output format where supported.
`seed`	`integer`	No	—	—
`reasoning_effort`	`string`	No	`low`, `medium`, `high`	—
`modalities`	`string[]`	No	—	—
`audio`	`object`	No	—	—

Full field definitions, nested objects and referenced schemas are available in the downloadable specification.

Request example

export NEON_API_KEY="YOUR_API_KEY"
curl https://neon-api.com/v1/chat/completions \
  -H "Authorization: Bearer $NEON_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "YOUR_MODEL_ID",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}'

Responses

Fields vary by model and protocol. The schema below describes the documented successful response; streams use protocol-specific events.

Status	Meaning
200	Successful response
400	Invalid request
429	Rate limited

Response schema

Field	Type	Required	Constraints	Meaning
`id`	`string`	No	—	Identifier returned for this result or task.
`object`	`string`	No	—	—
`created`	`integer`	No	—	—
`model`	`string`	No	—	Exact published model ID.
`choices`	`object[]`	No	—	Generated completion candidates.
`usage`	`Usage`	No	—	Usage reported by the selected protocol.
`system_fingerprint`	`string`	No	—	—

Download the user API OpenAPI specification

See errors and streaming & tasks.

Chat Completions