API

Manifest exposes both OpenAI and Anthropic-format endpoints on one proxy. Point your client at the Manifest URL, send auto as the model, and routing picks the real model behind the scenes.

Base URL

Mode	URL
Cloud	`https://app.manifest.build`
Self-hosted	`http://localhost:2099` (or your custom port)

Authentication

Every request requires a Manifest harness key:

Authorization: Bearer mnfst_YOUR_KEY_HERE

Generate a key from the dashboard’s Harnesses page. Keys always start with mnfst_.

Endpoints

Method	Path	Format	Use it for
`POST`	`/v1/chat/completions`	OpenAI	Most clients (OpenAI SDK, LangChain, Vercel AI SDK, custom HTTP)
`POST`	`/v1/responses`	OpenAI Responses	Codex, `*-pro`, `o1-pro`, deep-research models
`POST`	`/v1/messages`	Anthropic	Anthropic SDK, Claude Code, anything that speaks the Messages API
`GET`	`/v1/models`	OpenAI	Listing the models your harness can route to

The proxy translates between formats internally, so you can send an OpenAI-shaped request and Manifest will reshape it before forwarding to an Anthropic-only model. The reverse works too.

Chat completions

curl -X POST http://localhost:2099/v1/chat/completions \
  -H "Authorization: Bearer mnfst_YOUR_KEY_HERE" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "auto",
    "messages": [
      {"role": "user", "content": "What is the capital of France?"}
    ]
  }'

The body is forwarded verbatim to the resolved provider, with model rewritten to the actual model ID. All standard OpenAI fields (temperature, max_tokens, tools, tool_choice, response_format, stream, etc.) pass through.

Anthropic messages

curl -X POST http://localhost:2099/v1/messages \
  -H "Authorization: Bearer mnfst_YOUR_KEY_HERE" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "auto",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Listing models

GET /v1/models returns the models your harness can reach, in OpenAI format. The first entry is always auto (routing); the rest are the real model IDs from your connected providers.

curl http://localhost:2099/v1/models \
  -H "Authorization: Bearer mnfst_YOUR_KEY_HERE"

Send auto to let Manifest route, or send any listed model ID to skip routing and go straight to that provider. If you send a model ID that is not in this harness-specific list, Manifest returns M302: Model not available. See Routing → Route a specific model.

Inspect model capabilities

Add ?capabilities=true to include known capability metadata for each concrete model. Without this query parameter, the response keeps the standard OpenAI model-list shape.

curl "http://localhost:2099/v1/models?capabilities=true" \
  -H "Authorization: Bearer mnfst_YOUR_KEY_HERE"

{
  "object": "list",
  "data": [
    {
      "id": "auto",
      "object": "model",
      "created": 0,
      "owned_by": "manifest"
    },
    {
      "id": "openai/gpt-5.4-mini-subscription",
      "object": "model",
      "created": 0,
      "owned_by": "openai",
      "capabilities": {
        "input_modalities": ["text", "image"],
        "output_modalities": ["text"],
        "features": ["stream", "tools"],
        "supported_endpoints": ["/responses"]
      }
    }
  ]
}

Field	Meaning
`input_modalities`	Input types the model accepts, such as `text` or `image`
`output_modalities`	Output types the model can produce
`features`	Known feature support: `stream` and `tools`
`supported_endpoints`	API endpoint formats the model supports

Capability fields are optional. A missing field means that support is unknown, not that the model does not support it. Manifest omits the entire capabilities object when it has no known metadata for a model. The synthetic auto model never includes capabilities because it can resolve to a different model for each request. Concrete model IDs remain directly routable exactly as listed, including IDs with the -subscription suffix.

Inspect model costs

Add ?cost=true to include known token prices for each concrete model. Prices are in USD per million tokens. Without this query parameter, the response keeps the standard OpenAI model-list shape.

curl "http://localhost:2099/v1/models?cost=true" \
  -H "Authorization: Bearer mnfst_YOUR_KEY_HERE"

{
  "object": "list",
  "data": [
    {
      "id": "auto",
      "object": "model",
      "created": 0,
      "owned_by": "manifest"
    },
    {
      "id": "openai/gpt-5.4-mini-subscription",
      "object": "model",
      "created": 0,
      "owned_by": "openai",
      "cost": {
        "input": 0.25,
        "output": 2
      }
    },
    {
      "id": "openrouter/example-free-model",
      "object": "model",
      "created": 0,
      "owned_by": "openrouter",
      "cost": {
        "input": 0,
        "output": 0
      }
    }
  ]
}

Field	Meaning
`input`	USD per million input tokens
`output`	USD per million output tokens

A zero value means the model has no per-token charge, as with some free or subscription-backed routes. If one price is unknown, Manifest omits only that field. If both prices are unknown, Manifest omits the entire cost object. The synthetic auto model never includes cost because its concrete model is selected for each request. To inspect both metadata types in one response, combine the query parameters: ?capabilities=true&cost=true.

Streaming

Set "stream": true to get an SSE stream back. The stream format matches the upstream protocol: OpenAI-style data: {...} chunks for /v1/chat/completions, Anthropic event blocks for /v1/messages. Routing and fallback both work with streams. If the primary model fails before the first chunk, the request restarts on the fallback. If it fails mid-stream, the connection closes. There’s no silent mid-stream retry.

Errors

The proxy returns a standard JSON error envelope:

{
  "error": {
    "message": "Limit exceeded: cost usage ($1.23) exceeds $1.00 per day",
    "type": "limit_exceeded",
    "code": 429
  }
}

Status	Meaning
`401`	Invalid or missing `Authorization` header
`402`	Manifest Free plan quota reached (`error.code = PLAN_LIMIT_REQUESTS`, M204), or provider billing/quota error from the upstream
`424`	Fallback chain exhausted (all configured models failed)
`429`	Hard limit hit (M200), or Manifest rate limit tripped
`5xx`	Upstream provider error (triggers fallback)

Status 424 is the only one that does not trigger a fallback. Manifest returns it itself when the chain is exhausted, so re-routing it would loop forever.

Rate limits

Self-hosted instances default to 100 requests per 60 seconds per harness. Override with THROTTLE_TTL and THROTTLE_LIMIT (Environment variables). Cloud rate limits are tied to your plan and shown in the dashboard.

Response headers

Every response carries routing headers so your client can see which model and tier handled the request, without parsing the response body.

Getting Started

Self-hosting

Features

Providers

Reference

Base URL

Authentication

Endpoints

Chat completions

Anthropic messages

Listing models

Inspect model capabilities

Inspect model costs

Streaming

Errors

Rate limits

Response headers

​Base URL

​Authentication

​Endpoints

​Chat completions

​Anthropic messages

​Listing models

​Inspect model capabilities

​Inspect model costs

​Streaming

​Errors

​Rate limits

​Response headers

Base URL

Authentication

Endpoints

Chat completions

Anthropic messages

Listing models

Inspect model capabilities

Inspect model costs

Streaming

Errors

Rate limits

Response headers