> For the complete documentation index, see [llms.txt](https://helpcenter.paperguide.ai/llms.txt).
> Use it to discover all available pages before exploring further.

# API Overview

Paperguide API overview for searching research papers and checking usage limits in your app or workflow.

## Overview

Use the Paperguide API to search academic papers and check how many API calls your account has used.

## Base URL

Send all requests to:

```bash
https://api.paperguide.ai/v1
```

## Authentication

Add your API key to the `x-api-key` header on every request. Create API keys in **Settings > API Keys** in the Paperguide dashboard.

<Callout kind="info" collapsed="false">

Keep API keys on your server and out of client-side code.

```bash
x-api-key: pg_api_your_key_here
```

</Callout>

## Available endpoints

The API currently includes two endpoints:

- **`GET /search`** — Search across academic papers using keyword and semantic matching.
- **`GET /usage`** — Check your current usage for the billing period, including quota and per-minute rate.

## Rate limits and quotas

Your plan sets both your monthly API quota and your per-minute request limit. If you go over either limit, the API returns `429 Too Many Requests`.

| Plan | Monthly calls | Rate limit |
| ---- | ------------- | ---------- |
| Free | 10            | 5 req/min  |
| Plus | 100           | 15 req/min |
| Pro  | 500           | 30 req/min |
| Enterprise | Usage-based | Contact us |

Enterprise pricing is usage-based. Contact us for Enterprise access. Enterprise usage is billed at `$0.01` per API call and supports up to 50 papers per request.

## Common errors

The API returns JSON errors when a request fails.

| Status | Meaning |
| ------ | ------- |
| `400`  | Invalid request parameters |
| `401`  | Missing or invalid API key |
| `429`  | Rate limit or monthly quota exceeded |
| `500`  | Internal server error |

## Next steps

Open the endpoint pages for request details, parameters, and example responses.

<Columns cols={2}>
  <Card
    title="Search API"
    href="/api-search"
    icon="search"
    cta="Open page"
  />
  <Card
    title="Usage API"
    href="/api-usage"
    icon="bar-chart"
    cta="Open page"
  />
</Columns>