21st Agents SDK vs Devin: Pricing and Ratings Compared (2026)
Entry prices and free plans as read on each vendor's pricing page, and user ratings as published on review sites, for 21st Agents SDK and Devin side by side. This page compares data; it is not a hands-on review.
On the data: On the data below, 21st Agents SDK leads on lower entry price and a free plan. We do not name an overall winner for this pair.
Short on time? Here's the quick answer
Based on published vendor pricing and features and on public review data, here's who should pick what:
21st Agents SDK
The fastest way to integrate AI agents with built-in UI and essential features into your applications.
Best for you if:
- • You want a free tier before you commit
Devin
AI software engineer by Cognition Labs
Best for you if:
- • You want AI software engineer
| At a Glance | 21st Agents SDK | Devin |
|---|---|---|
Starts at | Free plan, paid from $6/mo, billed monthly Builder plan | From $500/mo, billed monthly Team plan |
Category | AI Agents Developer Tools | AI Coding Developer Tools |
Rating | n/a | n/a |
Free plan | Yes | No |
Watch out for | These $ are billed yearly. The page says save 25% vs quarterly. | Overage fees of $2.25/ACU on Core plan |
Choose 21st Agents SDK or Devin?
Choose 21st Agents SDK if
- You want a free tier before you commit
- You want accelerates AI agent integration
- You want provides essential features out-of-the-box
- Budget matters ($6/mo, billed monthly vs $500/mo, billed monthly)
- You work in AI agents, not AI coding
Choose Devin if
- You want AI software engineer
- You want end-to-end tasks
- You work in AI coding, not AI agents
In-Depth Analysis
21st Agents SDK
The fastest way to integrate AI agents with built-in UI and essential features into your applications.
21st.dev publishes yearly list prices: Builder $6/month, Builder + AI $15/month, Team $7.50/seat/month (2–50 seats).
Watch out
These $ are billed yearly. The page says save 25% vs quarterly.
Strengths
- Pro: Accelerates AI agent integration
- Pro: Provides essential features out-of-the-box
- Pro: Compatible with popular web technologies
- Pro: Handles complex aspects like memory and tool use
Key features
Devin
AI software engineer by Cognition Labs
Devin's pricing is fair for individual developers with the $20/month Core plan, offering a pay-as-you-go model.
Watch out
Overage fees of $2.25/ACU on Core plan
Strengths
- Pro: AI software engineer
- Pro: End-to-end tasks
- Pro: Good for automation
- Pro: Innovative approach
- Pro: Active development
Weaknesses
- Con: Waitlist/limited access
- Con: Expensive
- Con: Accuracy varies
- Con: Not replacement for devs
- Con: Early stage
Key features
Plans and prices: 21st Agents SDK vs Devin
| Tool | Plans and prices | Source |
|---|---|---|
| 21st Agents SDK |
| 21st.dev/pricing read Oct 23, 2026 |
| Devin |
| cognition-labs.com read Oct 4, 2026 |
Prices as read on each vendor's own pricing page on the date shown. Plans are listed per tool and are not matched against the other tool's plans: a plan name or price in one column says nothing about the same row in the other. Details on 21st Agents SDK pricing and Devin pricing.
Key Takeaways
21st Agents SDK
- Lower entry price: $6/mo, billed monthly vs $500/mo, billed monthly
- Has a free plan
Devin
- Choose if you want AI software engineer by Cognition Labs
What the data shows
On the data below, 21st Agents SDK leads on lower entry price and a free plan. We do not name an overall winner for this pair.
- 21st Agents SDK has the lower entry price: $6/mo, billed monthly (Builder) against $500/mo, billed monthly (Team) for Devin.
- Only 21st Agents SDK has a free plan.
Criteria: user rating (only above 20 reviews on both sides, gap of 0.2 or more), entry price (only on the same billing basis), free plan. How we rate
Frequently Asked Questions
How do 21st Agents SDK and Devin compare in 2026?
On the data below, 21st Agents SDK leads on lower entry price and a free plan. We do not name an overall winner for this pair. 21st Agents SDK has the lower entry price: $6/mo, billed monthly (Builder) against $500/mo, billed monthly (Team) for Devin. Only 21st Agents SDK has a free plan.
What are 21st Agents SDK and Devin used for?
21st Agents SDK: The fastest way to integrate AI agents with built-in UI and essential features into your applications. Devin: AI software engineer by Cognition Labs.
What does 21st Agents SDK cost vs Devin?
21st Agents SDK's cheapest paid plan is Builder at $6/mo, billed monthly; it also has a free plan. Devin's cheapest paid plan is Team at $500/mo, billed monthly. Prices read on the vendors' pricing pages, latest check Oct 23, 2026.
What's the main difference between 21st Agents SDK and Devin?
21st Agents SDK's main strength: accelerates AI agent integration. Devin's main strength: AI software engineer.