StepFun

Step 3.5 Flash 2603

CTX256K

Reasoning · Tools

Input$0.10/M

Output$0.30/M

StepFun flash model for efficient multimodal reasoning, coding, and tool use

Open weightsApache 2.0853/1040

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StepFunTextCommon

Step 3.5 Flash 2603

StepFun flash model for efficient multimodal reasoning, coding, and tool use

step-3.5-flash-2603

Type: Text
Quality: Not rated yet
Context window: 256,000 tokens
Max output: 256,000 tokens
Input price: $0.10 / 1M tokens
Output price: $0.30 / 1M tokens
Cache read: $0.02 / 1M tokens
Cache write: —
Released: Apr 2, 2026
Knowledge cutoff: Jan 2025
Takes in: Text
Puts out: Text
Reasoning: Yes
Tool calling: Yes
Structured output: No
File attachments: No
Access: Open weights
License: Apache 2.0
Rarity: Common
Set number: 853/1040

Open StepFun docs Where to run it 6 Evolution 1/2 Meet its creature Battle Phi-4-mini-reasoning

No matching Hugging Face repo was found, so this shows StepFun’s usual open-weight license. Check the model card before relying on it. Specs from models.dev, last changed Oct 18, 2026. Official source: platform.stepfun.ai.

How good is it?

Public leaderboard scores for Step 3.5 Flash 2603, refreshed daily from Epoch AI and LMArena.

No public leaderboard lists Step 3.5 Flash 2603 yet. Epoch AI and LMArena cover most chat, image, and video models from the big labs; embeddings, speech, and small open models mostly go unrated.

Where to run it

6 providers sell Step 3.5 Flash 2603 through an API. Prices are per million tokens, cheapest first.

CheapestEmpirioLabs AI$0.10 in · $0.30 out
From the labStepFun (Global)$0.10 in · $0.30 out

API providers

Provider	Input	Output	Context
EmpirioLabs AICheapest paid`step-3-5-flash-2603`	$0.10	$0.30	256K
NanoGPT`stepfun-ai/step-3.5-flash-2603`	$0.10	$0.30	262K
StepFun (China)`step-3.5-flash-2603`	$0.10	$0.30	256K
StepFun (Global)Official`step-3.5-flash-2603`	$0.10	$0.30	256K
StepFun Step Plan (China)`step-3.5-flash-2603`	—	—	256K
StepFun Step Plan (Global)`step-3.5-flash-2603`	—	—	256K

From models.dev and Hugging Face, checked daily. Resellers’ listings can lag behind their price pages, so confirm with the provider before you commit.

Face off

Current text models from other labs at a similar output price.