Codex 1 vs Mistral Medium 3.5
Codex 1 (2025) and Mistral Medium 3.5 (2026) compare a coding-specialized model against a standalone API model. Codex 1 ships a 192k-token context window, while Mistral Medium 3.5 ships a 256k-token context window. On SWE-bench Verified, Mistral Medium 3.5 leads by 5.5 pts. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: Codex 1 is coding-specialized model, while Mistral Medium 3.5 is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | Codex 1 | Mistral Medium 3.5 |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents and code generation | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, Agents, and Long context | Coding, RAG, and Agents |
| Context window | 192k | 256k |
| Cheapest output | - | $7.50/1M tokens |
| Provider routes | 0 tracked | 3 tracked |
| Shared benchmarks | 1 rows | SWE-bench Verified leader |
Decision tradeoffs
- Codex 1 uniquely exposes Code execution in local model data.
- Local decision data tags Codex 1 for Coding, Agents, and Long context.
- Mistral Medium 3.5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 5.5 points.
- Mistral Medium 3.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Mistral Medium 3.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Mistral Medium 3.5 uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Mistral Medium 3.5 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Codex 1
Unavailable
No complete token price in local provider data
Mistral Medium 3.5
$3,075
Cheapest tracked route/tier: Mistral AI Studio
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Codex 1 and Mistral Medium 3.5; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Code execution before moving production traffic.
- Mistral Medium 3.5 adds Vision, Multimodal, and Function calling in local capability data.
- No overlapping tracked provider route is sourced for Mistral Medium 3.5 and Codex 1; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Multimodal, and Function calling before moving production traffic.
- Codex 1 adds Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-05-16 | 2026-04-29 |
| Context window | 192k | 256k |
| Parameters | — | 128B |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Codex 1 | Mistral Medium 3.5 |
|---|---|---|
| Input price | - | $1.50/1M tokens |
| Output price | - | $7.50/1M tokens |
| Providers | - |
Capabilities
| Capability | Codex 1 | Mistral Medium 3.5 |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | Yes | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | No | Yes |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Codex 1 | Mistral Medium 3.5 |
|---|---|---|
| SWE-bench Verified | 72.1 | 77.6 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Codex 1 at 72.1 and Mistral Medium 3.5 at 77.6, with Mistral Medium 3.5 ahead by 5.5 points. The largest visible gap is 5.5 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Mistral Medium 3.5, multimodal input: Mistral Medium 3.5, function calling: Mistral Medium 3.5, tool use: Mistral Medium 3.5, structured outputs: Mistral Medium 3.5, and code execution: Codex 1. Both models share reasoning mode, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: Codex 1 has no token price sourced yet and Mistral Medium 3.5 has $1.50/1M input tokens. Provider availability is 0 tracked routes versus 3. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Codex 1 when coding workflow support are central to the workload. Choose Mistral Medium 3.5 when long-context analysis, larger context windows, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Codex 1 or Mistral Medium 3.5?
Mistral Medium 3.5 supports 256k tokens, while Codex 1 supports 192k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Codex 1 or Mistral Medium 3.5 open source?
Codex 1 is listed under Proprietary. Mistral Medium 3.5 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Codex 1 or Mistral Medium 3.5?
Mistral Medium 3.5 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Codex 1 or Mistral Medium 3.5?
Mistral Medium 3.5 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, Codex 1 or Mistral Medium 3.5?
Both Codex 1 and Mistral Medium 3.5 expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Codex 1 and Mistral Medium 3.5?
Codex 1 is available on the tracked providers still being sourced. Mistral Medium 3.5 is available on Mistral AI Studio, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.