---
title: Claude API vs Claude.ai (web app)
slug: claude-api-vs-claude-ai
type: agent-comparison
a: claude-api
b: claude-ai
canonical: https://top-agent-skills.com/compare/claude-api-vs-claude-ai
rubric: 1.0
---

# Claude API vs Claude.ai (web app)

Side-by-side for SKILL.md agent Skills: install model, shell access, native support, and how many Skills are verified on each.

## At a glance

| | Claude API | Claude.ai |
| --- | --- | --- |
| Vendor | Anthropic | Anthropic |
| Native SKILL.md support | Yes | Yes |
| Verified skills indexed | 13 | 31 |
| Install model | POST /v1/skills | Upload via Settings |
| Shell / Bash access | Sandboxed | Sandboxed |
| Tagline | Claude API + Skills SDK. Pre-built skill_id values plus custom uploads via /v1/skills. | The Claude web app. Enable code execution, then upload skills as zips under Customize → Skills. |

## Overlap

- Verified on both: 9
- Only Claude API: 4
- Only Claude.ai: 22

## Which should you pick?

Both support SKILL.md natively, so the choice is about ecosystem fit. Pick Claude API for Anthropic integrations and the workflows it makes easiest; pick Claude.ai (web app) for Anthropic integrations and its specific surface.

Many teams use both — Skills with the SKILL.md spec are portable, and 9 of the skills indexed here are verified on both agents.

Per-agent rankings: https://top-agent-skills.com/skills-for-claude-api · https://top-agent-skills.com/skills-for-claude-ai

## Common questions

**Which is better for SKILL.md skills, Claude API or Claude.ai (web app)?**

Both support SKILL.md natively. Claude API has 13 verified skills indexed here; Claude.ai (web app) has 31. 9 skills work on both.

**Can I use the same Skill on Claude API and Claude.ai (web app)?**

9 of the skills indexed here work on both. The SKILL.md spec is shared, so most skills run cleanly on both — the exceptions are skills that depend on agent-specific tools (Bash, Workflows, MCP patterns).

**How do I install a Skill on Claude API?**

POST your Skill zip to /v1/skills. You receive a skill_id. Reference it in your messages request — the model loads the Skill on demand.

**How do I install a Skill on Claude.ai (web app)?**

Enable code execution under Settings → Capabilities, then go to Customize → Skills and upload the Skill folder as a ZIP. The Skill becomes available in all your Claude.ai conversations.

**Which agent should I pick for most skill workflows?**

Both support skills natively. Pick by ecosystem fit: Claude API for Anthropic customers, Claude.ai (web app) for Anthropic customers.

---

_Top Agent Skills. Machine-readable twin of https://top-agent-skills.com/compare/claude-api-vs-claude-ai._