Devstral 2 vs Leanstral: Which is Better in 2026?
A comprehensive comparison of Devstral 2 and Leanstral covering features, pricing, use cases, and which tool is the right choice for your needs.
⚡ Quick Verdict
Choose Devstral 2 if:
- →You need a broader feature set (12 features vs 9)
- →You need 72.2% on swe-bench verified (devstral 2, 123b) — state-of-the-art among open-weight models at launch or 68.0% on swe-bench verified (devstral small 2, 24b) — matches models 5× its size
- →Your primary focus is llm-apis
Choose Leanstral if:
- →You need 120b total parameters, 6b active (sparse moe) — efficient inference at scale or apache 2.0 open weights — full self-hosting permitted
- →Your primary focus is coding & development
Devstral 2 vs Leanstral: At a Glance
Pricing Comparison: Devstral 2 vs Leanstral
Understanding the pricing differences between Devstral 2 and Leanstral is crucial for making the right choice. Here's how their plans compare side by side.
💡 Pricing takeaway: Both Devstral 2 and Leanstral offer free tiers, making it easy to try before you buy. Compare the specific plans to find the best value for your use case.
Feature-by-Feature Comparison
Here's how every feature from Devstral 2 and Leanstral stacks up.
What Makes Each Tool Unique
🔵 Unique to Devstral 2
Features available in Devstral 2 but not in Leanstral:
- ✓72.2% on SWE-bench Verified (Devstral 2, 123B) — state-of-the-art among open-weight models at launch
- ✓68.0% on SWE-bench Verified (Devstral Small 2, 24B) — matches models 5× its size
- ✓256K context window — supports full codebase ingestion and multi-file edits
- ✓Up to 7× more cost-efficient than Claude Sonnet on real-world coding tasks (Mistral human evals)
- ✓42.8% win rate vs. 28.6% loss rate against DeepSeek V3.2 in independent human evaluation via Cline
- ✓Mistral Vibe CLI: open-source terminal agent for autonomous end-to-end code automation
- ✓Multi-file editing: tracks framework dependencies, detects failures, retries with corrections
- ✓Fine-tuning support for specific languages or enterprise codebases
- ✓Devstral 2: modified MIT license — Devstral Small 2: Apache 2.0
- ✓5× smaller than DeepSeek V3.2 (123B vs ~671B) at comparable benchmark performance
- ✓Devstral Small 2 runs locally on consumer hardware — single H100 or equivalent
- ✓Compatible with Cline, Continue, and other VS Code coding agent integrations
🟣 Unique to Leanstral
Features available in Leanstral but not in Devstral 2:
- ✓120B total parameters, 6B active (sparse MoE) — efficient inference at scale
- ✓Apache 2.0 open weights — full self-hosting permitted
- ✓Free API endpoint via Mistral La Plateforme
- ✓Zero-setup integration in Mistral Vibe via /leanstall command
- ✓MCP support: trained to maximize performance with lean-lsp-mcp
- ✓FLTEval benchmark: 26.3 at pass@2 — beats Claude Sonnet 4.6 (23.7) at 1/15th the cost
- ✓At pass@16, reaches 31.9 — beats Sonnet by 8 points and Haiku by 8.9 points
- ✓Outperforms Qwen3.5-397B-A17B and Kimi-K2.5-1T-A32B despite far fewer active parameters
- ✓New FLTEval evaluation suite for real proof engineering (FLT project PRs), not just competition math
Use Case Recommendations
Best for: Devstral 2
Mistral AI's next-generation open-weight coding model family, released December 9, 2025. Devstral 2 is a 123B-parameter dense transformer with a 256K context window, achieving 72.2% on SWE-bench Verified under a modified MIT license — currently free via the Mistral API. Devstral Small 2 (24B, Apache 2.0) scores 68.0% on SWE-bench Verified and runs on consumer hardware. Up to 7× more cost-efficient than Claude Sonnet at real-world coding tasks per Mistral's human evaluations. Ships alongside Mistral Vibe, an open-source terminal CLI for end-to-end code automation.
Ideal use cases:
- •Teams or individuals who need 72.2% on swe-bench verified (devstral 2, 123b) — state-of-the-art among open-weight models at launch
- •Teams or individuals who need 68.0% on swe-bench verified (devstral small 2, 24b) — matches models 5× its size
- •Teams or individuals who need 256k context window — supports full codebase ingestion and multi-file edits
- •Teams or individuals who need up to 7× more cost-efficient than claude sonnet on real-world coding tasks (mistral human evals)
- •Anyone focused on mistral workflows
- •Anyone focused on coding model workflows
Best for: Leanstral
Leanstral is Mistral AI's open-source code agent purpose-built for Lean 4, the proof assistant used for formal verification of mathematics and mission-critical software. Released March 16, 2026, it's a 120B-parameter sparse MoE model with 6B active parameters — designed to operate in realistic formal repositories, not just isolated math competition problems. Apache 2.0 license, free API endpoint, and integrated into Mistral Vibe for zero-setup use.
Ideal use cases:
- •Teams or individuals who need 120b total parameters, 6b active (sparse moe) — efficient inference at scale
- •Teams or individuals who need apache 2.0 open weights — full self-hosting permitted
- •Teams or individuals who need free api endpoint via mistral la plateforme
- •Teams or individuals who need zero-setup integration in mistral vibe via /leanstall command
- •Anyone focused on mistral workflows
- •Anyone focused on lean4 workflows
🔧 Other llm-apis Tools to Consider
Devstral 2 and Leanstral aren't the only options. Here are other popular tools in the same space:
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Windsurf
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Bolt
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Frequently Asked Questions
Is Devstral 2 better than Leanstral?
It depends on your needs. Devstral 2 offers 12 key features including 72.2% on SWE-bench Verified (Devstral 2, 123B) — state-of-the-art among open-weight models at launch and 68.0% on SWE-bench Verified (Devstral Small 2, 24B) — matches models 5× its size, while Leanstral provides 9 features including 120B total parameters, 6B active (sparse MoE) — efficient inference at scale and Apache 2.0 open weights — full self-hosting permitted. Devstral 2 uses a freemium model with a free tier, while Leanstral is freemium with free access available. Choose based on which features and pricing model align with your requirements.
Is Devstral 2 cheaper than Leanstral?
Both tools have similar pricing structures. Both tools offer free tiers, so you can try each before committing. Always check the official websites for the most current pricing.
Can I use Devstral 2 and Leanstral together?
Yes, many users combine Devstral 2 and Leanstral in their workflow. Devstral 2 excels at 72.2% on swe-bench verified (devstral 2, 123b) — state-of-the-art among open-weight models at launch, while Leanstral shines with 120b total parameters, 6b active (sparse moe) — efficient inference at scale. Using both allows you to leverage the strengths of each tool, though this means managing two subscriptions — though free tiers can help manage costs.
What's the main difference between Devstral 2 and Leanstral?
Devstral 2 is primarily a llm-apis tool focused on mistral's sota open-weight coding model — 72.2% swe-bench, free api, while Leanstral focuses on coding & development with mistral's open-source lean 4 proof agent — formal verification at low cost. They serve different primary use cases despite being alternatives.