---
title: "Ceisium Search Developer Resources | API and OpenAPI"
description: "Find the Ceisium Search API, OpenAPI contract, authentication guide, capability discovery, Agent Skill, and integration documentation."
canonical: https://ceisium.com/developers/
---

> For the complete documentation and public content index, see [llms.txt](/llms.txt). This page is the Markdown alternative to the canonical HTML page.

Ceisium Search developer resources

# Build with the Ceisium Search API.

Use these stable resources to discover the public REST surface, understand authentication, create typed calls, and integrate project-scoped website search.

## Machine contracts

[OpenAPI 3.1 Typed operations, unique operation IDs, request and response schemas, errors, and bearer authentication.](https://ceisium.com/openapi.json) [API capabilities Public JSON discovery for the current Ceisium Search REST surface.](https://api.ceisium.com/v1/capabilities) [Agent content index A generated directory of current documentation, trust pages, changes, and articles.](https://ceisium.com/llms.txt) [Ceisium Search Agent Skill Portable setup, Search API, safety, and troubleshooting instructions for coding agents.](https://ceisium.com/skill.md)

## Documentation

-   [Quickstart](https://ceisium.com/docs/)
    
    Add a source, crawl it, create a Search key, and run the first query.
    
-   [Search API and authentication](https://ceisium.com/docs/search-api/)
    
    Choose a Browser/public or Server key and handle requests, results, and errors.
    
-   [UI components](https://ceisium.com/docs/ui-components/)
    
    Connect the Search API to a website interface.
    
-   [Usage and limits](https://ceisium.com/docs/usage/)
    
    Understand search volume, crawling, plans, and limits.
    

## First Search request

Create a project-scoped Server Search key in the Ceisium Search application. Store it in an environment variable, then send the project ID and query.

```
curl https://api.ceisium.com/v1/search \
  -H "Authorization: Bearer $CEISIUM_SEARCH_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "project_id": "prj_example",
    "query": "search setup",
    "top_k": 5
  }'
```

## Authentication boundary

Search is not anonymous. Browser/public keys need exact allowed origins. Server keys belong only in trusted backend code. Never put a Server key in a client bundle, public repository, log, screenshot, or support message. The public health and capabilities endpoints do not return tenant data or credentials.