How to use GPT OSS 120B from Synthetic with API Key

Learn how to access and use GPT OSS 120B with your Synthetic API key through TypingMind. Get started with this powerful AI model in minutes.

Synthetic.new is a privacy-focused AI platform offering private access to multiple open-source LLMs through simple flat-rate subscriptions starting at $20/month for 125 requests per 5 hours or $60/month for 1250 requests.

The platform provides access to 19+ always-on models including Llama 3 variants with up to 128K token context windows, specialized coding models, and task-specific LoRA adapters, with guaranteed privacy through no training on user data and automatic deletion within 14 days.

Key features include OpenAI-compatible API for integration with tools like Roo, Cline, and Octofriend, web-based chat interface, on-demand model launching from Hugging Face repositories on cloud GPUs with separate per-minute billing, predictable pricing without per-token charges, and support for large context coding tasks.

The platform prioritizes developer workflows and code generation with strong privacy guarantees and cost-effective access to powerful open-source models.

Official Documentation: https://synthetic.new/pricing

GPT OSS 120B Overview

Model NameGPT OSS 120B
ProviderSynthetic
Model IDhf:openai/gpt-oss-120b
Release DateAug 5, 2025
Last UpdatedAug 5, 2025
Context Window128,000 tokens
Max Output32,768 tokens
Pricing /1M tokens$0.1 input
$0.1 output
Input Modalitiestext
Output Modalitiestext
Capabilities
ReasoningTool CallingTemperature ControlOpen Weights

Complete Setup Guide

1

Get Your Synthetic API Key

First, you'll need to obtain an API key from Synthetic. This key allows you to access their AI models directly and pay only for what you use.

  1. Visit Synthetic's API console
  2. Sign up or log in to your account
  3. Navigate to the API keys section
  4. Generate a new API key (copy it immediately as some providers only show it once)
  5. Save your API key in a secure password manager or encrypted note

⚠️ Important: Keep your API key secure and never share it publicly. Store it safely as you'll need it to connect with TypingMind.

2

Configure TypingMind with Synthetic API Key

  1. Open TypingMind in your browser
  2. Click the "Settings" icon (gear symbol)
  3. Navigate to "Models" section
  4. Click "Add Custom Model"
  5. Fill in the model information:
    Name: hf:openai/gpt-oss-120b via Synthetic (or your preferred name)
    Endpoint: https://api.synthetic.new/openai/v1/chat/completions
    Model ID: hf:openai/gpt-oss-120b
    Context Length: Enter the model's context window (e.g., 128000 for hf:openai/gpt-oss-120b)
    Synthetic Endpoint URL input fieldhf:openai/gpt-oss-120bhttps://api.synthetic.new/openai/v1/chat/completionshf:openai/gpt-oss-120b via Synthetichttps://www.typingmind.com/model-logo.webp128000
  6. Add custom headers by clicking "Add Custom Headers" in the Advanced Settings section:
    Authorization: Bearer <SYNTHETIC_API_KEY>:
    X-Title: typingmind.com
    HTTP-Referer: https://www.typingmind.com
  7. 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.
  8. Click "Test" to verify the configuration
  9. If you see "Nice, the endpoint is working!", click "Add Model"
3

Start chatting with GPT OSS 120B

Now you can start chatting with GPT OSS 120B through TypingMind:

  • Select GPT OSS 120B 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
The best frontend AI chat for hf:openai/gpt-oss-120b via OpenRouter API KeyThe best frontend AI chat for hf:openai/gpt-oss-120b via OpenRouter API Keyhf:openai/gpt-oss-120bThe best frontend AI chat for hf:openai/gpt-oss-120b via OpenRouter API Key

💡 Pro tips for better results:

Frequently Asked Questions

Do I need a subscription to use GPT OSS 120B?

No! With Synthetic API, you pay only for what you use with no monthly subscription. Add credits to your Synthetic account and pay as you go. TypingMind is also a one-time purchase, not a subscription.

How much will it cost to use GPT OSS 120B?

GPT OSS 120B costs $0.1/1M input tokens and $0.1/1M output tokens. A typical conversation might cost $0.01-0.10 depending on length.

Can I use other models besides GPT OSS 120B?

Yes! With Synthetic API + TypingMind, you can access all Synthetic models. 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). Synthetic handles API calls securely. Check Synthetic's data policy for specifics.

Can I use GPT OSS 120B for commercial projects?

Yes! Check Synthetic's terms of service for specific commercial use policies. TypingMind supports commercial use.