Devstral Small 2 vs Step 3.5 Flash 2603
Devstral Small 2 comes out ahead, 67 to 62 on our weighted score.
- Our pick
Mistral AIDevstral Small 2
67/100- ECI—
- Price$0.10 / $0.30
- Context262K
StepFunStep 3.5 Flash 2603
62/100- ECI—
- Price$0.10 / $0.30
- Context256K
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Make it a three-way comparison.
Devstral Small 2 is our pick
Devstral Small 2 is the better all-round choice, scoring 67/100 against Step 3.5 Flash 2603 (62). It leads on inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceSame priceDevstral Small 2 $0.15 · Step 3.5 Flash 2603 $0.15 per 1M tokens (3:1 blend)
- Longest contextDevstral Small 2Devstral Small 2 262,144 · Step 3.5 Flash 2603 256,000 tokens
- Widest inputsDevstral Small 2Devstral Small 2: Text, Images · Step 3.5 Flash 2603: Text
- Self-hostingAll open weightsEvery model here can be downloaded and run on your own hardware
| Measure | Weight | Devstral Small 2 | Step 3.5 Flash 2603 |
|---|---|---|---|
| Price | 50% | 89 | 89 |
| Inputs & features | 30% | 50 | 35 |
| Context window | 20% | 37 | 36 |
| Overall | 100% | 67/100 | 62/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Devstral Small 2Mistral AI | Step 3.5 Flash 2603StepFun |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $0.10 | $0.10 |
| Output | $0.30 | $0.30 |
| Cached input | — | $0.02 |
| Blended (3:1) | $0.15 | $0.15 |
| Long-context rate | Same rate | Same rate |
| Price source | Median of 1 providers | Official StepFun (Global) API |
| Limits | ||
| Context window | 262,144 tokens (best) | 256,000 tokens |
| Max output | 262,144 tokens (best) | 256,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | No |
| PDFs | No | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | No | Yeslow · high |
| Tool calling | Yes | Yes |
| Structured output | No | No |
| Availability | ||
| Weights | OpenApache-2.0 | Open |
| API model ID | — | step-3.5-flash-2603 |
| API providers | 1 | 3 (best) |
| Released | Dec 9, 2025 | Apr 2, 2026 |
| Knowledge cutoff | Dec 2025 | Jan 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Devstral Small 2$1.60
- Step 3.5 Flash 2603$1.60
Which should you choose?
Which is better: Devstral Small 2 or Step 3.5 Flash 2603?
Devstral Small 2 is the better all-round choice, scoring 67/100 against Step 3.5 Flash 2603 (62). It leads on inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Devstral Small 2 or Step 3.5 Flash 2603?
Devstral Small 2 and Step 3.5 Flash 2603 cost the same: $0.10 input / $0.30 output per million tokens.
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Devstral Small 2 has not been scored yet and Step 3.5 Flash 2603 has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Devstral Small 2 and Step 3.5 Flash 2603 yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.
Which has the bigger context window?
Devstral Small 2 has the largest context window at 262,144 tokens, against 256,000 for Step 3.5 Flash 2603. Maximum output per response: Devstral Small 2 up to 262,144, Step 3.5 Flash 2603 up to 256,000 tokens.
Which can read images, PDFs, audio or video?
Devstral Small 2 accepts text and images; Step 3.5 Flash 2603 accepts text. Devstral Small 2 handles the widest range of inputs.
Are any of these open source?
Yes, both publish their weights (Apache-2.0), so you can self-host them.
Which is newer?
Step 3.5 Flash 2603 is the newest, released Apr 2, 2026. Devstral Small 2 came out Dec 9, 2025. Knowledge cutoff: Devstral Small 2 Dec 2025, Step 3.5 Flash 2603 Jan 2025.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
