---
title: "Human Cell Atlas (HCA)"
description: "| 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 |"
type: skill
canonical_url: https://claudary.paisolsolutions.com/skills/hca
source: "Claudary"
difficulty: intermediate
author: "Claude Code Knowledge Pack"
date: 2026-07-10T11:25:09.937Z
license: CC-BY-4.0
attribution: "Human Cell Atlas (HCA) — Claudary (https://claudary.paisolsolutions.com/skills/hca)"
---

# Human Cell Atlas (HCA)
| 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 |

## Overview

# 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.

---

Source: [Claudary](https://claudary.paisolsolutions.com/skills/hca) · https://claudary.paisolsolutions.com