Overview
Devstral Medium and Devstral Small 1.1, released July 10, 2025, were Mistral AI's mid-2025 update to its Devstral coding-agent line, developed in collaboration with All Hands AI. Devstral Small 1.1 is an open Apache 2.0 model with 24 billion parameters, while Devstral Medium is a higher-performing model available only through the Mistral API and enterprise deployment.
Devstral Small 1.1 scores 53.6% on SWE-Bench Verified — an improvement of about 6.8 points over the original Devstral Small — and was positioned as state-of-the-art among open models for code agents. Devstral Medium reaches 61.6% on SWE-Bench Verified, which Mistral compared favourably to Gemini 2.5 Pro and GPT-4.1 at roughly a quarter of the price. Both models use a 128K-token context window.
Devstral Small 1.1 is fine-tuned from Mistral-Small-3.1-24B-Base-2503 and is text-only (the vision encoder was removed for coding-agent use). It supports both Mistral's function-calling format and XML tool-call formats, and emphasises generalization across prompts and agentic frameworks. Both models in this generation have since been deprecated in favour of the December 2025 Devstral 2 family.
| Released | 2025-07-10 |
|---|---|
| License | Devstral Small 1.1: Apache 2.0; Devstral Medium: proprietary (API only) |
| Weights | Open weights |
| Parameters | Devstral Small 1.1: 24B; Devstral Medium: not disclosed |
| Context | 128K |
| Architecture | Dense decoder-only Transformer; Devstral Small 1.1 fine-tuned from Mistral-Small-3.1-24B-Base-2503 (text-only, vision encoder removed) |
| Knowledge cutoff | 2025 |
| Modalities | Text |
| Status | Deprecated |
Benchmarks
Scores on a 0–100 scale (25-point gridlines); higher is better. Each benchmark links to its published source.
Pricing
| Input | $0.10 / 1M tokens (Devstral Small 1.1); $0.40 / 1M tokens (Devstral Medium) per 1M tokens |
|---|---|
| Output | $0.30 / 1M tokens (Devstral Small 1.1); $2.00 / 1M tokens (Devstral Medium) per 1M tokens |
Mistral API pricing as published in the July 2025 announcement.
Strengths
- Devstral Small 1.1 is open Apache 2.0 and was state-of-the-art among open code-agent models at release
- Devstral Medium reaches 61.6% SWE-Bench Verified at a fraction of comparable proprietary-model pricing
- 128K-token context for multi-file and long-prompt software-engineering workflows
- Supports both Mistral function-calling and XML tool-call formats
- Built with All Hands AI for strong generalization across agentic frameworks
Best for
- Open, self-hostable coding agents (Devstral Small 1.1)
- Higher-accuracy agentic software engineering via the Mistral API (Devstral Medium)
- Resolving real GitHub issues in OpenHands-style scaffolds
- Enterprise on-premise coding deployments and custom fine-tuning (Devstral Medium)
How to access
| Provider | Model ID |
|---|---|
| Mistral AI ↗ | devstral-medium-2507 |
| Mistral AI ↗ | devstral-small-2507 |
Devstral — every version
The full lineage of the Devstral line, newest first. Every version has its own page — click any to compare specs, benchmarks and pricing.
| Version | Released | Context | License |
|---|---|---|---|
| Devstral 2 / Devstral Small 2current | 2025-12-09 | 256K | Devstral 2: Modified MIT; Devstral Small 2: Apache 2.0 |
| Devstral Medium & Small 1.1 (25.07) | 2025-07-10 | 128K | Devstral Small 1.1: Apache 2.0; Devstral Medium: proprietary (API only) |
| Devstral Small (25.05) | 2025-05-21 | 128K | Apache-2.0 |
FAQ
How do Devstral Medium and Devstral Small 1.1 differ?
Devstral Small 1.1 is a 24B open Apache 2.0 model scoring 53.6% on SWE-Bench Verified, suitable for self-hosting. Devstral Medium is API-only (proprietary) and scores 61.6% on SWE-Bench Verified, with higher accuracy and enterprise deployment options. Both use a 128K context window and were released July 10, 2025.
Is Devstral Small 1.1 open source?
Yes. Devstral Small 1.1 (model ID devstral-small-2507) is released under the permissive Apache 2.0 license with open weights on Hugging Face, fine-tuned from Mistral-Small-3.1-24B-Base-2503. Devstral Medium, by contrast, is proprietary and available only through the Mistral API or enterprise agreements.
What did Mistral compare Devstral Medium to?
Mistral stated that Devstral Medium's 61.6% on SWE-Bench Verified surpasses Gemini 2.5 Pro and GPT-4.1 for roughly a quarter of the price, positioning it on a new cost/performance point for agentic coding.
Are these models still available?
Both Devstral Medium and Devstral Small 1.1 have been deprecated and superseded by the December 2025 Devstral 2 family (Devstral 2 and Devstral Small 2). The open Devstral Small 1.1 weights remain downloadable on Hugging Face.