How to use GPT OSS 120B from Fireworks AI with API Key

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

Fireworks.ai is a high-performance generative AI platform that provides the fastest inference for open-source LLMs and multimodal models through a developer-friendly API.

The platform features a proprietary FireAttention engine delivering 50% faster speed and 250% higher throughput than standard engines, with support for popular models like LLaMA, Mixtral, DeepSeek, and Falcon. Key capabilities include serverless inference, advanced fine-tuning (LoRA, RLHF), function calling, batch processing, on-demand GPU access (NVIDIA H100/H200, AMD MI300X), and OpenAI-compatible APIs.

Official Documentation: https://fireworks.ai/docs/

GPT OSS 120B Overview

Model NameGPT OSS 120B
ProviderFireworks AI
Model IDaccounts/fireworks/models/gpt-oss-120b
Release DateAug 5, 2025
Last UpdatedAug 5, 2025
Context Window131,072 tokens
Max Output32,768 tokens
Pricing /1M tokens$0.15 input
$0.6 output
Input Modalitiestext
Output Modalitiestext
Capabilities
ReasoningTool CallingTemperature ControlOpen Weights

Complete Setup Guide

1

Get Your Fireworks AI API Key

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

  1. Visit Fireworks AI'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 Fireworks AI 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: accounts/fireworks/models/gpt-oss-120b via Fireworks AI (or your preferred name)
    Endpoint: https://api.fireworks.ai/inference/v1/chat/completions
    Model ID: accounts/fireworks/models/gpt-oss-120b
    Context Length: Enter the model's context window (e.g., 131072 for accounts/fireworks/models/gpt-oss-120b)
    Fireworks AI Endpoint URL input fieldaccounts/fireworks/models/gpt-oss-120bhttps://api.fireworks.ai/inference/v1/chat/completionsaccounts/fireworks/models/gpt-oss-120b via Fireworks AIhttps://www.typingmind.com/model-logo.webp131072
  6. Add custom headers by clicking "Add Custom Headers" in the Advanced Settings section:
    Authorization: Bearer <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 accounts/fireworks/models/gpt-oss-120b via OpenRouter API KeyThe best frontend AI chat for accounts/fireworks/models/gpt-oss-120b via OpenRouter API Keyaccounts/fireworks/models/gpt-oss-120bThe best frontend AI chat for accounts/fireworks/models/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 Fireworks AI API, you pay only for what you use with no monthly subscription. Add credits to your Fireworks AI 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 $0.15/1M input tokens and $0.6/1M 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 Fireworks AI API + TypingMind, you can access all Fireworks AI 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). Fireworks AI handles API calls securely. Check Fireworks AI's data policy for specifics.

Can I use GPT OSS 120B for commercial projects?

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