How to Use LLMs for Free ?

Learn how to use free LLMs with OpenRouter and online platforms like Grok. This technical guide covers OpenRouter APIs, setup, and API calls, with Apidog for streamlined testing. Discover free models and best practices for 2025.

Ashley Innocent

Ashley Innocent

13 May 2025

How to Use LLMs for Free ?

Large Language Models (LLMs) have transformed natural language processing, enabling developers to build sophisticated AI-driven applications. However, accessing these models often comes with costs. Fortunately, platforms like OpenRouter and various online services offer free access to LLMs through APIs, making it possible to experiment without financial commitment. This technical guide explores how to leverage free LLMs using OpenRouter and online platforms, detailing available APIs, setup processes, and practical implementation steps.

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Additionally, tools like Apidog streamline API testing and documentation, enhancing your development workflow. Download Apidog for free to simplify your API interactions and visualize LLM responses efficiently, ensuring seamless integration with OpenRouter and other platforms.
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Why Use Free LLMs?

LLMs, such as Meta’s Llama or Mistral’s Mixtral, power applications like chatbots, code generators, and text analyzers. Free access to these models eliminates cost barriers, enabling developers to prototype and deploy AI features. OpenRouter, a unified inference API, provides standardized access to multiple LLMs, while online platforms like GitHub Models offer user-friendly interfaces. By combining these with Apidog, you can test and debug API calls effortlessly, ensuring optimal performance.

Understanding OpenRouter and Its Role in Free LLM Access

OpenRouter is a powerful platform that aggregates LLMs from various providers, offering a standardized, OpenAI-compatible API. It supports both free and paid tiers, with free access to models like Llama 3 and Mistral 7B. OpenRouter’s key features include:

By using OpenRouter, developers access a diverse range of LLMs without managing multiple provider accounts. Apidog complements this by providing tools to test and visualize OpenRouter API calls, ensuring accurate request formatting.

Free OpenRouter APIs for LLMs

OpenRouter offers access to several free LLMs, each with unique architectures and capabilities. Below is a comprehensive list of free models available as of April 2025, based on technical specifications from recent analyses:

Mixtral 8x22B Instruct (Mistral AI)

Scout 109B (xAI)

Kimi-VL-A3B-Thinking (Moonshot AI)

Nemotron-8B-Instruct (NVIDIA)

Llama 3 8B Instruct (Meta AI)

Mistral 7B Instruct (Mistral AI)

Gemma 2/3 Instruct (Google)

Qwen 2.5 Instruct (Alibaba)

These models are accessible via OpenRouter’s free tier, though limits apply (e.g., 30 requests/minute, 60,000 tokens/minute). Developers must sign up and obtain an API key, with phone verification sometimes required.

Best Free AI Models You Can Use on OpenRouter
This article provides a technical exploration of the top 13 free AI models available on OpenRouter, analyzing their architectures, parameter distributions, context handling, and performance characteristics.

Other Free Online Platforms for LLMs

Beyond OpenRouter, several platforms provide free access to LLMs, each with distinct advantages:

GitHub Models

GitHub Models - GitHub Docs
Find and experiment with AI models for free.

Cloudflare Workers AI

Google AI Studio

These platforms complement OpenRouter by offering alternative access methods, from browser-based interfaces to API-driven integrations. Apidog enhances productivity by providing a unified interface to test and document these APIs.

Setting Up OpenRouter for Free LLM Access

To use OpenRouter’s free APIs, follow these steps:

Create an Account

Understand Rate Limits

Install Prerequisites

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Configure Your Environment

Making an API Call with OpenRouter

OpenRouter’s API follows an OpenAI-compatible format, making it straightforward to integrate. Below is a step-by-step guide to making an API call, including a sample Python script.

Step 1: Prepare the Request

Step 2: Write the Code

Here’s a Python example using the requests library to query Llama 3 8B Instruct:

import requests
import json

# Configuration
api_key = "your_openrouter_api_key"
url = "https://openrouter.ai/api/v1/chat/completions"
headers = {
    "Authorization": f"Bearer {api_key}",
    "Content-Type": "application/json"
}

# Request payload
payload = {
    "model": "meta-ai/llama-3-8b-instruct",
    "messages": [
        {"role": "user", "content": "Explain the benefits of using LLMs for free."}
    ],
    "temperature": 0.7,
    "max_tokens": 500
}

# Make the API call
response = requests.post(url, headers=headers, data=json.dumps(payload))

# Process the response
if response.status_code == 200:
    result = response.json()
    print(result["choices"][0]["message"]["content"])
else:
    print(f"Error: {response.status_code}, {response.text}")

Step 3: Test with Apidog

Step 4: Handle Responses

Step 5: Optimize Usage

This script demonstrates a basic API call. For production, add error handling, rate limiting, and logging. Apidog simplifies these tasks by providing a user-friendly interface for request management.

Best Practices for Using Free LLMs

To maximize the benefits of free LLMs, follow these technical best practices:

Select the Right Model

Optimize API Calls

Handle Rate Limits

Ensure Data Privacy

Monitor Performance

Leverage Quantization

By adhering to these practices, you ensure efficient and reliable use of free LLMs, with Apidog enhancing your workflow through streamlined testing and documentation.

Challenges and Limitations

While free LLMs offer significant advantages, they come with challenges:

Rate Limits

Context Window Restrictions

Performance Variability

Data Privacy Concerns

Dependency on Provider Infrastructure

Despite these limitations, free LLMs remain a powerful tool for developers, especially when paired with Apidog for robust API management.

Integrating Free LLMs into Your Applications

To integrate free LLMs into your applications, follow this workflow:

Define Requirements

Select a Platform

Develop the Integration

Deploy and Monitor

Iterate and Optimize

This workflow ensures seamless integration, with Apidog playing a critical role in testing and documentation.

Conclusion

Free LLMs, accessible via OpenRouter and online platforms, empower developers to build AI-driven applications without financial barriers. By using OpenRouter’s unified API, you can tap into models like Llama 3, Mixtral, and Scout, while platforms like Grok and GitHub Models offer alternative access methods. Apidog enhances this process by providing tools to test, debug, and document API calls, ensuring a smooth development experience. Start experimenting today by signing up for OpenRouter and downloading Apidog for free. With the right approach, free LLMs can unlock endless possibilities for your projects.

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