Apertus 8B vs Step 3.5 Flash
Step 3.5 Flash comes out ahead, 62 to 56 on our weighted score, though Apertus 8B is 17% cheaper per token.
Swiss AI
Apertus 8B
56/100- ECI—
- Price$0.10 / $0.20
- Context66K
- Our pick
StepFunStep 3.5 Flash
62/100- ECI—
- Price$0.10 / $0.30
- Context256K
Add a model
Make it a three-way comparison.
Step 3.5 Flash is our pick
Step 3.5 Flash is the better all-round choice, scoring 62/100 against Apertus 8B (56). It leads on inputs & features and context window. Apertus 8B wins on price. 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 priceApertus 8BApertus 8B $0.125 · Step 3.5 Flash $0.15 per 1M tokens (3:1 blend)
- Longest contextStep 3.5 FlashStep 3.5 Flash 256,000 · Apertus 8B 65,536 tokens
- Widest inputsSame inputsApertus 8B: Text · Step 3.5 Flash: Text
- Self-hostingAll open weightsEvery model here can be downloaded and run on your own hardware
| Measure | Weight | Apertus 8B | Step 3.5 Flash |
|---|---|---|---|
| Price | 50% | 93 | 89 |
| Inputs & features | 30% | 25 | 35 |
| Context window | 20% | 12 | 36 |
| Overall | 100% | 56/100 | 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 | Apertus 8BSwiss AI | Step 3.5 FlashStepFun |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $0.10 | $0.10 |
| Output | $0.20 (best) | $0.30 |
| Cached input | — | $0.02 |
| Blended (3:1) | $0.125 (best) | $0.15 |
| Long-context rate | Same rate | Same rate |
| Price source | Median of 1 providers | Official StepFun (Global) API |
| Limits | ||
| Context window | 65,536 tokens | 256,000 tokens (best) |
| Max output | 8,192 tokens | 256,000 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | 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 |
| API providers | 1 | 8 (best) |
| Released | Sep 2, 2025 | Jan 29, 2026 |
| Knowledge cutoff | Sep 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.
- Apertus 8B$1.40
- Step 3.5 Flash$1.60
Which should you choose?
Which is better: Apertus 8B or Step 3.5 Flash?
Step 3.5 Flash is the better all-round choice, scoring 62/100 against Apertus 8B (56). It leads on inputs & features and context window. Apertus 8B wins on price. 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, Apertus 8B or Step 3.5 Flash?
Apertus 8B is cheaper at $0.10 input / $0.20 output per million tokens (median across 1 API provider). Step 3.5 Flash costs $0.10 input / $0.30 output per million tokens (official StepFun (Global) API price). At a typical mix of three input tokens to one output token, that is $0.125 per million tokens for Apertus 8B versus $0.15 for Step 3.5 Flash (1.2× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Apertus 8B has not been scored yet and Step 3.5 Flash has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Apertus 8B and Step 3.5 Flash 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?
Step 3.5 Flash has the largest context window at 256,000 tokens, against 65,536 for Apertus 8B. Maximum output per response: Apertus 8B up to 8,192, Step 3.5 Flash up to 256,000 tokens.
Which can read images, PDFs, audio or video?
Apertus 8B accepts text; Step 3.5 Flash accepts text. They handle the same number of input types.
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 is the newest, released Jan 29, 2026. Apertus 8B came out Sep 2, 2025. Knowledge cutoff: Apertus 8B Sep 2025, Step 3.5 Flash 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.
