# Paper Instruments API

**Canonical:** https://apis.io/apis/paper-instruments/paper-instruments-api/  
**Provider:** Paper Instruments — https://apis.io/providers/paper-instruments/  
**Base URL:** https://api.paperinstruments.com  
**Documentation:** https://docs.paperinstruments.com/docs/ultramarine

Paper Instruments API is one of 2 APIs that [Paper Instruments](https://apis.io/providers/paper-instruments/) publishes on the [APIs.io](https://apis.io/) network, described by a machine-readable OpenAPI specification. This API exposes 6 JSON Schema definitions. The published artifact set on APIs.io includes an OpenAPI specification and 6 JSON Schemas.

Paper Instruments API as documented publicly: 8 operations. Contract generated from the documentation by API Evangelist (2026-10-29); not the provider's own document.

## Operations (8)

| Method | Path | Summary |
|---|---|---|
| GET | `/v1` | GET /v1 |
| POST | `/v1/chat/completions` | Create a chat completion. |
| POST | `/v1/messages` | Send a message to the Ultramarine API using the Anthropic Messages format. |
| GET | `/v1/models` | Lists available models. |
| GET | `/v1/models/{id}` | Retrieves one model. |
| GET | `/v1/pricing` | Returns the current rates without authentication. |
| POST | `/v1/responses` | POST /v1/responses |
| GET | `/v1/usage` | Call GET /v1/usage with an API key for organization usage in the current UTC calendar month. |

## Machine-readable artifacts (7)

- **OpenAPI** — https://artifacts.apis.io/paper-instruments/openapi/_ae-authored/paper-instruments-openapi-generated.yml
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-post-v1-chat-completions-request-schema.json
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-post-v1-responses-request-schema.json
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-post-v1-messages-request-schema.json
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-post-v1-responses-response-schema.json
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-post-v1-messages-response-schema.json
- **JSONSchema** — https://artifacts.apis.io/paper-instruments/json-schema/paper-instruments-get-v1-usage-response-schema.json

## Other Paper Instruments APIs (1)

- [Compliance GraphQL API](https://apis.io/apis/paper-instruments/compliance-graphql/)

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/paper-instruments/paper-instruments-api/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/paper-instruments/.