API Documentation - Free Inference Pricing API

Authentication

API keys are required for all requests. Sign up with your email to get a free key.

1Click "Get API Key" or go to the Sign Up page
2Enter your email address
3Click the magic link in the email
4Your API key is displayed on the dashboard

Pass your API key in the Authorization header:

Authorization: Bearer ***

Example:

$ curl -H "Authorization: Bearer ***" \
     https://api.inferenceindexer.ai/v1/sit/composite/latest

Endpoints

Each endpoint is a card. All paths are prefixed with the API base URL.

GET/v1/sit/composite/latest

Returns the current SIT-Composite index value, including tier breakdowns.

Parameters

None

Example Request

$ curl -H "Authorization: Bearer ***" \
     https://api.inferenceindexer.ai/v1/sit/composite/latest

Example Response (200 OK)

{
  "date": "2026-08-03",
  "composite": {
    "price_per_m": 2.84,
    "index_points": 784.5,
    "change_24h": -1.2,
    "change_7d": -3.1,
    "change_30d": -12.4
  },
  "tiers": {
    "frontier": { "price_per_m": 35.20, "change_24h": -0.8, "models": 8 },
    "standard": { "price_per_m": 1.25, "change_24h": -1.5, "models": 156 },
    "budget": { "price_per_m": 0.42, "change_24h": -2.1, "models": 78 }
  },
  "spread": { "price_per_m": 34.78, "change_24h": -1.9 }
}

GET/v1/sit/composite/history?days=30

Returns historical SIT-Composite values.

Parameters

Parameter	Type	Required	Description
days	integer	No	Number of days to return (default: 30, max: 365)
tier	string	No	Filter to a specific tier: frontier, standard, budget

Example Request

$ curl -H "Authorization: Bearer ***" \
     "https://api.inferenceindexer.ai/v1/sit/composite/history?days=30"

Example Response (200 OK)

{
  "history": [
    { "date": "2026-08-03", "price_per_m": 2.84, "index_points": 784.5 },
    { "date": "2026-08-02", "price_per_m": 2.87, "index_points": 792.8 },
    ...
  ]
}

GET/v1/models?tier=standard&sort=blended

Returns all tracked models with current pricing.

Parameters

Parameter	Type	Required	Description
tier	string	No	Filter by tier: frontier, standard, budget, micro
provider	string	No	Filter by provider name
sort	string	No	Sort by: blended, input, output, sit_score (default: sit_score)
limit	integer	No	Max results (default: 50, max: 315)

Example Request

$ curl -H "Authorization: Bearer ***" \
     "https://api.inferenceindexer.ai/v1/models?tier=standard&sort=blended"

Example Response (200 OK)

{
  "count": 315,
  "models": [
    {
      "model_id": "deepseek/deepseek-v4-reasoner",
      "name": "DeepSeek V4 Reasoner",
      "provider": "DeepSeek",
      "tier": "frontier",
      "input_price_per_m": 0.55,
      "output_price_per_m": 2.19,
      "blended_price_per_m": 1.53,
      "sit_score": 0.04,
      "context_length": 128000,
      "change_24h": -3.0,
      "change_7d": -8.0
    },
    ...
  ]
}

GET/v1/models/{model_id}

Returns detailed pricing and metadata for a single model.

Parameters

Parameter	Type	Required	Description
model_id	string	Yes	The model ID (e.g. openai/gpt-5.6)

Example Request

$ curl -H "Authorization: Bearer ***" \
     https://api.inferenceindexer.ai/v1/models/openai/gpt-5.6

Example Response (200 OK)

{
  "model_id": "openai/gpt-5.6",
  "name": "OpenAI: GPT-5.6",
  "provider": "OpenAI",
  "tier": "frontier",
  "input_price_per_m": 2.50,
  "output_price_per_m": 10.00,
  "blended_price_per_m": 4.75,
  "sit_score": 0.12,
  "context_length": 256000,
  "change_24h": 0.0,
  "change_7d": -2.1
}

GET/v1/models/{model_id}/history?days=90

Returns historical price data for a single model.

Parameters

Parameter	Type	Required	Description
model_id	string	Yes	The model ID
days	integer	No	Days of history (default: 30, max: 365 on free tier)

Example Request

$ curl -H "Authorization: Bearer ***" \
     "https://api.inferenceindexer.ai/v1/models/openai/gpt-5.6/history?days=90"

Example Response (200 OK)

{
  "model_id": "openai/gpt-5.6",
  "history": [
    { "date": "2026-08-03", "blended_price_per_m": 4.75 },
    { "date": "2026-08-02", "blended_price_per_m": 4.80 },
    ...
  ]
}

Rate Limits

Plan	Requests/day	Requests/minute	History access
Public (no key)	100	10	7 days
Free (email)	1,000	30	30 days
Paid (future)	50,000	100	365 days

Rate limit headers are included in every response:

X-RateLimit-Limit: 1000
X-RateLimit-Remaining: 987
X-RateLimit-Reset: 1691078400

Response Format

All responses are JSON. Timestamps are ISO 8601 UTC. Prices are in USD per million tokens.

Successful response (200 OK)

{
  "data": { ... },
  "meta": {
    "request_id": "req_abc123",
    "timestamp": "2026-08-03T15:00:00Z"
  }
}

Pagination (for list endpoints)

{
  "count": 315,
  "page": 1,
  "per_page": 50,
  "total_pages": 7,
  "next": "/v1/models?page=2"
}

Errors

Status Code	Meaning
200 OK	Success
400 Bad Request	Invalid parameter (check the error message)
401 Unauthorized	Missing or invalid API key
404 Not Found	Model or endpoint doesn't exist
429 Too Many	Rate limit exceeded. Check X-RateLimit-Reset header
500 Server Error	Something went wrong on our end. Retry after a few seconds

Error response format

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Rate limit of 1000 requests/day exceeded. Resets at 2026-08-04T00:00:00Z.",
    "documentation_url": "https://inferenceindexer.ai/api/docs#rate-limits"
  }
}