21st Agents SDK vs LangChain vs Obsidian
| Attribute | |||
|---|---|---|---|
| Category | Developer Tools | AI Agents & Assistants | Note-taking & Knowledge |
| Pricing | Paid | Free tier | Free tier |
| Starting price | $6/month | $39/month | $4/seat/month |
| Free tier | No | Yes | Yes |
| Free trial | No | No | No |
| Deployment | — | — | Cloud |
| API available | Unknown | Unknown | Unknown |
| Platforms | — | — | ios, android, windows, macos, linux |
| Certifications | — | — | — |
| Integrations | 1 | — | 2 |
| Company | — | — | Founded 2020 |
| Feature attributes | |||
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Unknown values show as “Unknown”/“—”. Nothing is inferred — see each tool page for sources.