Step 3.5 Flash

Apr 2026
Older versionReplace withStep 3.7 FlashNewer versionSolar Mini 4Cheaper, as goodGPT-6 LunaBetterMiMo v2.6 ProOpen weights
Step 3.5 Flash
Compare in
on
—per task?
$0.10 / $0.30per 1M in / outcache $0.02
129 tok/sfirst token in 3.3 s?
256Kcontext

Rankingin thinking mode?

Retired models are left out of the current rankings.

Alternatives?

ModelScoreCostPer taskWhat changes
CheaperLing 3.0 Flash VLthinkingOpen+45%-40%$0.06 / $0.18BetterGPT-6 Lunalow+27%+33%$0.005Function calling only with none · Chat Completions+3OpenMiMo v2.6 Prothinking×2.7+262%$0.13Pass back reasoning_content+3CheaperSolar Mini 4+42%-42%$0.37CheaperLing 3.0 Flash FinthinkingOpen+33%-40%$0.06 / $0.18

History

4 versions
171819Apr 26Release dateAA Intelligence Index 4.3.23.5 · Apr3.7
171819Apr 26Release dateAA Intelligence Index 4.3.23.5 · Apr3.7

Benchmarks

all categories
Chat & Knowledge
Humanity's Last Exam24.5
AA Omniscience Index-44.2
CritPt (physics)2.3
AA Intelligence Index 4.3.2≈17
AA Omniscience · Accuracy24.6
AA Omniscience · Hallucination Rate91.3
AA-LCR (long context) 1.163
GPQA Diamond82.6
Coding
Terminal-Bench Hard (version unstated)32.6
Agents & Tool Use
τ²-bench · AA87.4
Writing & Language
IFBench (instructions)66.5

FAQ

How much does Step 3.5 Flash cost?›

$0.10 per 1M input tokens and $0.30 per 1M output tokens; cached input $0.02 per 1M; cheapest via DeepInfra at $0.09 / $0.30.

Is Step 3.5 Flash free to use?›

There is no free API; the cheapest paid price is $0.09 per 1M input tokens.

How can I use Step 3.5 Flash?›

Through the API of DeepInfra, Featherless, SiliconFlow.

What is the context window of Step 3.5 Flash?›

256K tokens, with up to 256K output tokens.

When was Step 3.5 Flash released? Is there a newer version?›

Released 2026-04-02. It has been superseded by Step 3.7 Flash.

Is Step 3.5 Flash open source?›

No, Step 3.5 Flash is a closed model available through an API. The closest open-weights option here is MiMo v2.6 Pro.

Can Step 3.5 Flash read images?›

No, it accepts text only.

What is Step 3.5 Flash?›

Step 3.5 Flash is a closed language model from StepFun, released Apr 2026, the successor to Step 3.5 Flash.

What are the best alternatives to Step 3.5 Flash?›

Ling 3.0 Flash VL (cheaper), GPT-6 Luna (better), MiMo v2.6 Pro (open weights).