Is the OpenAI API Free? What You Can Use at No Cost

By the Zylo team · Updated June 8, 2026 · 4 min read

People ask whether the OpenAI API is free, and the honest answer has two parts. Getting an API key is free, and on Zylo AI you can use a gpt-5-nano-class Basic-tier model on the free Basic plan with no credit card — so yes, you can call a GPT-family model without paying. But the larger GPT models are not free: GPT-5.4 Mini and GPT-5.5 are premium models billed per token from credits on a paid plan. There is no perpetual free tier for the big models, on OpenAI directly or anywhere else, because running them costs real money. This guide clears up what is genuinely free, what is billed, and the common confusion between ChatGPT the app and the OpenAI API.

The free part, stated honestly

On Zylo the free Basic plan needs no credit card and gives you a daily allowance of roughly 200,000 tokens and 7,200 requests, with a rate limit of 10 requests per minute and up to 200,000 input characters per request. Within that allowance you can call a lightweight gpt-5-nano-class Basic-tier OpenAI model for text tasks — prototyping, drafting, classification, and small assistants. Basic-tier models are text only and not multimodal, and the free plan carries no credits, since credits come only with paid plans. So “free OpenAI API” truthfully means a free key, a free account, and a real daily allowance on a Basic-tier model. That is a usable starting point, not a loophole for unlimited frontier access, which does not exist. To put numbers on it, the daily Basic allowance of roughly 200,000 tokens covers several thousand short completions, which is plenty to wire up a feature, test prompt variations, and demo a working idea before any money is involved. The allowance also refreshes every day rather than draining like a one-off trial credit, so a small project can live on it indefinitely. What you should not expect is to run the heavier GPT models inside that free envelope, because those sit on a different tier for a real reason: they cost meaningfully more to serve. Treating the free allowance as your development and low-volume tier, and the paid plan as your production tier for premium GPT models, is the mental model that keeps the first invoice free of surprises.

The larger GPT models are premium

The GPT models people usually want for heavier work are premium and billed per token from credits on a paid plan (Go and up). At point-in-time June 2026 prices, GPT-5.4 Mini runs about $0.75 per million input tokens and $4.50 per million output tokens, while GPT-5.5 runs about $5 input and $30 output per million. Every model is billed at its base per-token rate with no markup on usage, and that per-token cost does not change with volume. The only platform fee is a flat 25 percent charged once when you add credits, never on what you spend. These figures are point-in-time, so confirm them on the live pricing page; the principle that matters is base-rate billing with a single up-front fee, not surprise charges on usage.

ChatGPT the app is not the API

A frequent source of confusion is treating ChatGPT and the OpenAI API as the same thing. ChatGPT is a consumer chat application with its own free and paid tiers meant for people typing into a web page. The API is for developers building software, and access, billing, and limits are entirely separate. A free ChatGPT account does not give you free API calls, and OpenAI’s own API has historically offered only occasional trial credits rather than a standing free tier. If your goal is to build an application rather than chat in a browser, you need API access with a clear allowance and predictable per-token pricing, which is a different product entirely.

GPT, Claude, and Gemini through one format

Zylo serves GPT models through the OpenAI-compatible format, so you keep the OpenAI SDK and change only the base URL to https://api.zyloai.net/v1 and your model-id string. The same key and endpoint also reach Claude, Gemini, DeepSeek, and more, with bare model ids and no vendor prefix, so moving from a free Basic-tier GPT to a premium model is a one-line change. If you are migrating an existing project, the switch from OpenAI guide walks through it; to compare options for your use case, read which AI API is best, browse the full models catalogue, and start with a free AI API key today.