---
title: "Human Cell Atlas (HCA)"
task: ""
lineage_type: import
upstream_source: https://github.com/K-Dense-AI/scientific-agent-skills/blob/9c9bd2e9/skills/database-lookup/references/hca.md
upstream_sha: 9c9bd2e9
imported_at: 2026-06-26
prompt_class: prompt
upstream_changes: accepted
author: upstream
validated: false
---

# Human Cell Atlas (HCA)

## Base URL
```
https://service.azul.data.humancellatlas.org/
```

## Auth
No auth required.

## Key Endpoints

| Endpoint | Description |
|----------|-------------|
| `/index/projects?size={n}&catalog=dcp2` | List/search projects |
| `/index/samples?size={n}&catalog=dcp2` | List/search samples |
| `/index/files?size={n}&catalog=dcp2` | List/search files |
| `/index/summary?catalog=dcp2` | Summary statistics |

## Example Calls
```
# List projects
https://service.azul.data.humancellatlas.org/index/projects?size=5&catalog=dcp2

# Summary stats
https://service.azul.data.humancellatlas.org/index/summary?catalog=dcp2
```

Supports JSON filter parameters for organ, species, library construction, etc.

## Response Format
JSON. `hits` array with project/sample/file metadata + pagination.

## Rate Limits
No published limits. Be reasonable.