Compare
Claude API vs Claude.ai (web app)
Side-by-side comparison of Claude API and Claude.ai (web app) for SKILL.md agent skills — install model, shell access, native support, skill count and best use cases.
Comparison
At a glance
| Dimension | Claude API | Claude.ai |
|---|---|---|
| Vendor | Anthropic | Anthropic |
| Native SKILL.md support | Yes | Yes |
| Verified skills indexed | 13 | 32 |
| 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. Upload skills as zips via Settings → Features. Pro/Max/Team/Enterprise. |
Both
9
Skills verified to work on both Claude API and Claude.ai.
Only Claude API
4
Indexed for Claude API but not yet verified on Claude.ai (web app).
Only Claude.ai
23
Indexed for Claude.ai (web app) but not yet verified on Claude API.
Verdict
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. Browse the per-agent rankings to see which Skills lead on each platform: Skills for Claude API · Skills for Claude.ai (web app).
FAQ
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 32. 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)?
Settings → Features → Skills. 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.
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