21st Agents SDK vs LangChain: 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 LangChain 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. 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 accelerates AI agent integration
LangChain
Build LLM-powered applications
Best for you if:
- • You want great for AI apps
| At a Glance | 21st Agents SDK | LangChain |
|---|---|---|
Starts at | Free plan, paid from $6/mo, billed monthly Builder plan | Free plan, paid from $39/mo, billed monthly Plus plan |
Category | AI Agents Developer Tools | AI Agents Developer Tools |
Rating | n/a | 4.6/5 G2 4.5 · SourceForge 5.0 127 reviews |
Free plan | Yes | Yes |
Watch out for | These $ are billed yearly. The page says save 25% vs quarterly. | Potential overage fees for traces |
Choose 21st Agents SDK or LangChain?
Choose 21st Agents SDK if
- You want accelerates AI agent integration
- You want provides essential features out-of-the-box
- Budget matters ($6/mo, billed monthly vs $39/mo, billed monthly)
Choose LangChain if
- You want great for AI apps
- You want active development
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
LangChain
Build LLM-powered applications
LangChain's pricing is quite generous, especially with a robust free Developer tier offering 5,000 traces/month.
Watch out
Potential overage fees for traces
Strengths
- Pro: Great for AI apps
- Pro: Active development
- Pro: Large community
Weaknesses
- Con: Fast changing API
- Con: Can be complex
Key features
Plans and prices: 21st Agents SDK vs LangChain
| Tool | Plans and prices | Source |
|---|---|---|
| 21st Agents SDK |
| 21st.dev/pricing read Oct 23, 2026 |
| LangChain |
| langchain.com/pricing read Oct 2, 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 LangChain pricing.
Key Takeaways
21st Agents SDK
- Lower entry price: $6/mo, billed monthly vs $39/mo, billed monthly
LangChain
- Choose if you want build LLM-powered applications
What the data shows
On the data below, 21st Agents SDK leads on lower entry price. We do not name an overall winner for this pair.
- Only LangChain has a published user rating (4.6/5 from 127 reviews); 21st Agents SDK has none we can show.
- 21st Agents SDK has the lower entry price: $6/mo, billed monthly (Builder) against $39/mo, billed monthly (Plus) for LangChain.
- Both have 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 LangChain compare in 2026?
On the data below, 21st Agents SDK leads on lower entry price. We do not name an overall winner for this pair. Only LangChain has a published user rating (4.6/5 from 127 reviews); 21st Agents SDK has none we can show. 21st Agents SDK has the lower entry price: $6/mo, billed monthly (Builder) against $39/mo, billed monthly (Plus) for LangChain. Both have a free plan.
What are 21st Agents SDK and LangChain used for?
21st Agents SDK: The fastest way to integrate AI agents with built-in UI and essential features into your applications. LangChain: Build LLM-powered applications.
What does 21st Agents SDK cost vs LangChain?
21st Agents SDK's cheapest paid plan is Builder at $6/mo, billed monthly; it also has a free plan. LangChain's cheapest paid plan is Plus at $39/mo, billed monthly; it also has a free plan. Prices read on the vendors' pricing pages, latest check Oct 23, 2026.
What's the main difference between 21st Agents SDK and LangChain?
21st Agents SDK's main strength: accelerates AI agent integration. LangChain's main strength: great for AI apps.