I tested over 10 providers to find the best free AI API in 2025

So you have a great idea for an AI app. Maybe it’s a smarter chatbot for your side hustle, a cool new content tool, or a feature that could actually make your team’s life easier. But then you slam into the usual wall: API fees. The thought of a massive bill just to test a prototype is enough to stop a great idea in its tracks. Trust me, I’ve been there.

The good news is that the AI scene is blowing up, and you don’t have to choose between your idea and your bank account anymore. A lot of top providers now have generous free plans that are perfect for building, testing, and even launching smaller projects. In this post, I’ll walk you through two main options: using a ready-made platform for specific things like customer support to get going instantly, or grabbing a free AI API to build something custom from scratch. I’ve put these tools through their paces to help you pick the right one for your next project, minus the financial stress.

What’s a free AI API, anyway?

Let’s quickly get on the same page about what we’re talking about. An Application Programming Interface (API) is basically a bridge that lets your app talk to a huge, pre-trained AI model living on a server somewhere else. You send it a request, like a text prompt or an image, and it sends back a response, like a generated paragraph or a new picture.

The real magic is that you get to tap into billions of dollars worth of R&D without needing a supercomputer in your basement or a PhD in machine learning. You just make an API call. This is the engine running behind most of the AI tools you see today, from chatbots and content writers to tools that analyze text or create images.

How I picked the best free AI API providers

To separate the good from the "meh," I came up with a few rules. I wasn’t just looking for any free tool; I was looking for stuff that’s actually useful for developers. Here’s what I was looking for:

• A genuinely useful free tier: The API had to offer a free plan that you can actually build and prototype with. No 7-day trials that die before you’ve even written a line of code. We want sustainable, free access.

• Good models: You should get access to modern, quality AI models, the ones you’ve actually heard of, like Google’s Gemini, Meta’s Llama, and the models from OpenAI.

• Easy to use: Because honestly, who has time to fight with terrible documentation? The providers on this list have clear instructions, simple authentication, and a developer experience that won’t make you want to throw your laptop out the window.

• Room to grow: While we’re focused on free, it’s good to know you won’t hit a wall if your project suddenly becomes popular. These platforms all have a clear path to a paid plan when you’re ready to scale.

The best free AI API providers at a glance

Provider	Key Models Available	Free Tier Highlights	Best For
eesel AI	N/A (Uses various)	Free plan for 1 bot, Copilot, Slack chat	Instantly deploying AI for customer support
Google AI Studio	Gemini family (2.5, Flash)	6M tokens/day, 180M/month	Prototyping with Google’s latest models
OpenRouter	50+ models (Claude, Llama, Mistral)	Free credits on signup, access to free models	Experimenting with a wide variety of models
Hugging Face	Thousands of open-source models	Free Inference API for community models	Leveraging specialized open-source models
OpenAI	GPT-3.5-Turbo, DALL-E 2	No free tier, but API is very cheap	Production apps needing high reliability
Groq	Llama 3, Mistral, Gemma	Generous free rate limits	Real-time applications needing low latency

A deep dive into the top 6 free AI API providers for 2025

Alright, let’s get into the nitty-gritty. Each of these platforms has its own vibe, and the best one for you will depend on what you’re trying to build.

1. eesel AI: The fastest way to automate customer support

I’m kicking things off with eesel AI because it’s the perfect example of a smart alternative to building from scratch. If your goal is an AI support bot, you could spend weeks wrestling with a free AI API, trying to manage context and conversation history. Or, you could just use eesel and have a professional-grade AI agent up and running in minutes.

eesel AI is a bit different. It’s not a raw API you code against. Instead, it’s a ready-to-go platform that hooks right into the tools you already use. It connects with helpdesks like Zendesk and Freshdesk and learns from your knowledge bases in Confluence, Google Docs, and even your team’s old support tickets. It’s a full, no-code solution for deploying AI agents, an agent-assist copilot, and website chatbots.

What’s great about it:

• You can get it running in minutes: The setup is truly self-serve. You can connect your knowledge sources with a few clicks and be ready to go without ever having to sit through a sales demo.

• It works with your existing setup: It fits right into your current workflow. No need to switch helpdesks or force your team to learn a new system.

• Powerful simulation mode: This feature is a huge plus. You can test your AI agent on thousands of your past tickets to see exactly how it would have performed. This helps you calculate a real ROI before you flip the switch for live customers.

What’s not so great:

• It’s built for a specific job. It’s designed for customer service, IT support, and internal helpdesks, so it’s not the right tool if you want to build a creative writing assistant or something similar.

Free Plan Details:

The free plan is solid for small teams trying to see if AI can help them. It gives you one bot, access to the AI Copilot which helps agents write replies, and an integration with Slack.

2. Google AI Studio: A powerful free AI API with the Gemini family

When it comes to raw APIs with a beefy free tier, Google is tough to beat. Google AI Studio is a web-based playground that makes it ridiculously easy to start tinkering with the Gemini API and gives you access to Google’s most powerful models.

It’s built for developers who want to prototype and build things quickly. You can get an API key in just a few clicks and start making calls almost immediately.

What’s great about it:

• The free limits are incredibly generous, up to 180 million tokens per month.

• You get access to the very capable, multimodal Gemini 2.5 Pro model.

• The documentation is excellent, and there’s a "cookbook" full of code examples to get you moving fast.

What’s not so great:

• Depending on where you live, the model availability can sometimes vary.

Free Plan Details:

You can use the Gemini API for free up to 6 million tokens per day and a whopping 180 million tokens per month. That’s more than enough for some serious development.

3. OpenRouter: A free AI API for the ultimate AI model buffet

If you’re the type of developer who loves to tinker and compare, then OpenRouter is going to be your new favorite toy. Think of it as a massive buffet for AI models. It brings together dozens of models from different providers, including all the open-source darlings, under one simple API.

This means you can swap between models like Claude 3.5 Sonnet, Llama 3, and Mistral just by changing one line in your API call. It’s the best way to compare models and find the perfect fit for your task without having to manage a bunch of different API keys and billing accounts.

What’s great about it:

• A huge variety of models, including many free and uncensored open-source options, all available with a single API key.

• The pay-as-you-go pricing is straightforward and easy to understand.

• Perfect for A/B testing different models to see which one performs best for your needs.

What’s not so great:

• For some of the high-end, proprietary models, it might be a tiny bit more expensive than going directly to the provider.

Free Plan Details:

OpenRouter gives you some free credits when you sign up to test out any model. It also usually has a few models that are completely free to use for testing.

4. Hugging Face: The hub for a free AI API with open-source AI

Hugging Face is pretty much the heart of the open-source AI world. It’s a platform hosting tens of thousands of models that researchers and developers have built for almost any task you can think of, from text generation and translation to audio analysis and computer vision.

Their free Inference API is an amazing resource. It lets you use any of these public models without having to download, configure, and host them yourself. It’s the easiest way to tap into specialized, fine-tuned models for more niche jobs.

What’s great about it:

• You’ll find an incredible selection of specialized models here that you won’t find on the big commercial platforms.

• It has a vibrant, helpful community and tons of examples.

• Great for projects that need a model trained on a very specific type of data.

What’s not so great:

• The free API has rate limits, so it’s mainly for low-traffic apps or development work, not for something that needs to handle a high volume of requests.

Free Plan Details:

The Inference API is free for all public models on the platform, you just have to stay within their rate limits.

5. OpenAI: The one that started it all

Okay, we have to talk about OpenAI. They might have gotten rid of their free trial credits, but their API is still the benchmark for performance and reliability. For a lot of developers, it’s the default choice for apps that need to be rock-solid.

And for testing, models like gpt-3.5-turbo are so inexpensive they’re almost free. A few dollars will buy you millions of tokens, which is plenty to build and test a complete application.

What’s great about it:

• Super reliable with great uptime and well-written docs.

• gpt-3.5-turbo provides a great mix of speed, smarts, and low cost for development.

What’s not so great:

• There’s no truly free tier anymore. You have to add at least $5 in prepaid credits to your account to get an API key.

Free Plan Details:

None. But the cheap cost of their older models makes it a very affordable choice for developers working on a small budget.

6. Groq: A free AI API that’s a speed demon

The team over at Groq is taking a different approach. They built their own custom hardware called Language Processing Units (LPUs) that are designed to do one thing: run large language models incredibly fast. Their API has the fastest response times out there, which makes it perfect for real-time applications where every millisecond counts.

If you’re building a chatbot or a conversational agent where lag would ruin the experience, Groq is a fantastic choice. Their API is also designed to be compatible with OpenAI’s, so you can often swap it into your existing code without much fuss.

What’s great about it:

• It’s ridiculously fast. The speed feels almost instant.

• It supports popular and powerful open-source models like Llama 3 and Mistral.

What’s not so great:

• The model selection is smaller than what you’ll find on platforms like OpenRouter or Hugging Face.

Free Plan Details:

Groq has a very generous free tier with high rate limits, giving you plenty of room to build and test your apps.

This video provides a great overview of the best free LLM APIs available so you can start building AI projects without breaking the bank.

A few tips for working with any free AI API

Whichever tool you end up choosing, here are a couple of things to keep in mind.

• Pro Tip #1: "Free" isn’t always free. A free AI API doesn’t mean your project costs nothing. Your development time is valuable. For a common problem like customer support, building a solution from the ground up is a huge job. A platform like eesel AI can deliver business results almost overnight, saving you weeks or months of coding.

• Pro Tip #2: Set usage caps. If you switch to a paid plan on any of these platforms, the very first thing you should do is set up billing alerts and hard spending limits. This will save you from a nasty surprise at the end of the month.

• Pro Tip #3: Cache your results. If you’re making the same API calls over and over, think about storing the responses. This one simple trick can slash the number of calls you make, helping you stay within your free limits and keeping your bill low if you ever upgrade.

Using a free AI API to build smarter, not just harder

Here’s the main takeaway: in 2025, there are amazing free options for any developer looking to build with AI. Your choice really boils down to what you’re trying to do.

For general projects where you need flexibility, raw APIs from Google AI Studio, OpenRouter, and Groq give you a ton of power for next to nothing. But for specific, high-value tasks like automating your company’s customer support, a specialized platform is almost always the faster and cheaper path in the long run. It lets you focus on the results, not the plumbing.

If you want to see just how quickly you can automate your support and give your customers a better experience, try eesel AI for free. You can connect your helpdesk and see a full simulation of how your own AI agent would perform in under five minutes.