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Ann NgUse step-3.5-flash:free via OpenRouter API on TypingMind
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token. It is a reasoning model that is incredibly speed efficient even at long contexts.
StepFun: Step 3.5 Flash (free) Overview
| Full Name | StepFun: Step 3.5 Flash (free) |
| Provider | StepFun |
| Model ID | stepfun/step-3.5-flash:free |
| Release Date | Jan 29, 2026 |
| Context Window | 256,000 tokens |
| Pricing /1M tokens | $ for input $ for output |
| Supported Input Types | text |
| Supported Parameters | frequency_penaltyinclude_reasoningmax_tokensreasoningstoptemperaturetoolstop_p |
Complete Setup Guide
Create OpenRouter Account
- Visit openrouter.ai
- Click "Sign In" and create an account (free)
- Verify your email address
- You'll receive $1 in free credits to test models
Get Your OpenRouter API Key
- Log in to OpenRouter dashboard
- Go to "API Keys" section in the menu
- Click "Create API Key"
- Give it a name (e.g., "TypingMind")
- Copy your API key (starts with "sk-or-v1-...")
Add Credits to OpenRouter (Optional)
- Go to "Credits" in OpenRouter dashboard
- Click "Add Credits"
- Choose amount ($5 minimum, $20 recommended for testing)
- Complete payment (credit card or crypto)
- Credits never expire!
Configure TypingMind with OpenRouter API Key
Method 1: Direct Import (Recommended)
- Open TypingMind in your browser
- Click the "Settings" icon (gear symbol)
- Navigate to "Manage Models" section
- Click "Add Custom Model"
- Select "Import OpenRouter" from the options
- Enter your OpenRouter API key from Step 1
- Click "Check API Key" to verify the connection
- Choose which models you want to add from the list (you can add multiple at once)
- Click "Import Models" to complete the setup
Method 2: Manual Custom Model Setup
- Open TypingMind in your browser
- Click the "Settings" icon (gear symbol)
- Navigate to "Models" section
- Click "Add Custom Model"
- Fill in the model information:Name:
stepfun/step-3.5-flash:free via OpenRouter(or your preferred name)Endpoint:https://openrouter.ai/api/v1/chat/completionsModel ID:stepfun/step-3.5-flash:freeContext Length: Enter the model's context window (e.g., 256000 for stepfun/step-3.5-flash:free)
stepfun/step-3.5-flash:freehttps://openrouter.ai/api/v1/chat/completionsstepfun/step-3.5-flash:free via OpenRouterhttps://www.typingmind.com/model-logo.webp256000 - Add custom headers by clicking "Add Custom Headers" in the Advanced Settings section:Authorization:
Bearer <OPENROUTER_API_KEY>:X-Title:typingmind.comHTTP-Referer:https://www.typingmind.com - Enable "Support Plugins (via OpenAI Functions)" if the model supports the "functions" or "tool_calls" parameter, or enable "Support OpenAI Vision" if the model supports vision.
- Click "Test" to verify the configuration
- If you see "Nice, the endpoint is working!", click "Add Model"
Start chatting with stepfun/step-3.5-flash:free
Now you can start chatting with the stepfun/step-3.5-flash:free model via OpenRouter on TypingMind:
- Select your preferred stepfun/step-3.5-flash:free model from the model dropdown menu
- Start typing your message in the chat input
- Enjoy faster responses and better features than the official interface
- Switch between different AI models as needed
stepfun/step-3.5-flash:freePro tips for better results:
- Use specific, detailed prompts for better responses (How to use Prompt Library)
- Create AI agents with custom instructions for repeated tasks (How to create AI Agents)
- Use plugins to extend stepfun/step-3.5-flash:free capabilities (How to use plugins)
- Upload documents and images directly to chat for AI analysis and discussion (Chat with documents)
Why TypingMind + OpenRouter?
- Best-in-class UI: TypingMind's interface is far superior to standard chat UIs
- Model flexibility: Switch between StepFun: Step 3.5 Flash (free) and 200+ models instantly
- Cost control: Pay only for what you use through OpenRouter
- One-time purchase: Buy TypingMind once, use forever with any OpenRouter model
- Data privacy: Your conversations stored locally, not on external servers
Frequently Asked Questions
Do I need a subscription to use StepFun: Step 3.5 Flash (free)?
No! Through OpenRouter, you pay only for what you use with no monthly subscription. Add credits to your OpenRouter account and they never expire. TypingMind is also a one-time purchase, not a subscription.
How much will it cost to use StepFun: Step 3.5 Flash (free)?
It costs 0 for input and 0 for output via OpenRouter. A typical conversation might cost $0.01-0.10 depending on length. Start with $5-10 in credits to test.
Can I use other models besides StepFun: Step 3.5 Flash (free)?
Yes! With OpenRouter + TypingMind, you get access to 200+ models including GPT-4, Claude, Gemini, Llama, Mistral, and many more. Switch between them instantly in TypingMind.
Is my data private and secure?
Yes! TypingMind stores conversations locally (web version in browser, desktop version on your device). OpenRouter handles API calls securely and doesn't train on your data. Check each provider's data policy for specifics.
Can I use StepFun: Step 3.5 Flash (free) for commercial projects?
Yes! Check StepFun's terms of service for specific commercial use policies. OpenRouter and TypingMind both support commercial use.
What if StepFun: Step 3.5 Flash (free) is unavailable?
OpenRouter allows you to configure fallback models. If StepFun: Step 3.5 Flash (free) is down, it can automatically route to your backup choice. You can also manually switch models in TypingMind anytime.
How do I cancel or get a refund?
OpenRouter: No subscriptions to cancel. Unused credits remain in your account forever.
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