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How to run OpenAI GPT models in your browser

OpenAI’s API blocks browser calls — a free OpenRouter key is the honest route, and it takes two minutes.

What it is, and when to pick it

Here is the plain truth: OpenAI’s API returns no CORS headers, so a browser page that tries to call api.openai.com is blocked before the request even lands — that is OpenAI’s setup, not this site’s. So this site never claims direct OpenAI support. The route that works: an OpenRouter key. It runs the same GPT models (gpt-5-nano, gpt-4o-mini and friends) from this page, billed through your OpenRouter account, and it is free to create.

Step by step

  1. Create an account at OpenRouter — Google, GitHub, or email; no card. openrouter.ai

  2. Open the Keys page and click “Create Key”, then copy the sk-or-v1- value — it is shown only once. openrouter.ai/keys

  3. Optional: add credits on the Credits page — $5 covers hundreds of runs, and “:free” model variants need no balance. openrouter.ai/credits

  4. In the AI resume tailor, choose OpenRouter and pick a GPT model such as gpt-5-nano or gpt-4o-mini.

What the key looks like

sk-or-v1-…

The key you paste here is an OpenRouter key. A native OpenAI key (sk-…, platform.openai.com/api-keys) is for server-side apps — a browser page cannot use it.

What it actually costs

  • The OpenRouter key is free; GPT usage bills through OpenRouter.
  • gpt-5-nano ≈ $0.05/$0.40 and gpt-4o-mini ≈ $0.15/$0.60 per million tokens (OpenRouter list prices sampled 2026-11-14 — estimates).
  • A typical tailored resume costs about $0.002–0.01.
  • “:free” model variants need no balance at all.

Paste it into Practical Web Tools

In the AI resume tailor, choose OpenRouter, paste the sk-or-v1-… key, and pick a GPT model from the model list. Your key stays in your browser; we never receive it. Open the AI resume tailor.

If something goes wrong

You pasted an OpenAI key (sk-…) and got “That key was rejected”
That is expected: browsers cannot call api.openai.com (no CORS headers), so this page does not accept OpenAI keys. Create an OpenRouter key instead — it runs the same GPT models.
401 — “That key was rejected”
The OpenRouter key was mistyped, clipped, or revoked. Create a fresh one at openrouter.ai/keys and paste it in full.
429 — “Provider rate limit hit”
Wait the time the provider asked for, then run again. If a “:free” GPT variant stays queued, a paid model skips the free queue.

Quick Answer

OpenAI’s API sends no CORS headers, so a browser cannot call it directly — no website can, from any page. To run GPT models (gpt-5-nano, gpt-4o-mini) from a browser tool, create a free OpenRouter key at https://openrouter.ai/keys (sk-or-v1-…), optionally add $5 of credits, and choose a GPT model in the tool with OpenRouter as the provider. The key never leaves your browser.

Key Facts

  • OpenAI’s API returns no CORS headers — browsers block direct calls (verified 2026-11-14)
  • This site never claims direct OpenAI support; GPT models route through OpenRouter
  • One free OpenRouter key (sk-or-v1-…) runs GPT, Claude, Gemini, Llama, Grok, DeepSeek and GLM
  • gpt-5-nano ≈ 0.40 per million tokens via OpenRouter (estimate, 2026-11-14)
  • A typical tailored resume costs about $0.002–0.01

Frequently Asked Questions

Can I paste my OpenAI API key here?

No. OpenAI’s endpoint sends no CORS headers, so the browser blocks the call before it reaches OpenAI. A free OpenRouter key runs the same GPT models and works from the browser.

Is this affiliated with OpenAI?

No. This site is independent; GPT models run through OpenRouter, an aggregator that bills many providers’ models on one account.

Does using OpenRouter cost more than OpenAI directly?

Prices are OpenRouter’s list prices, shown as an estimate before each run, so you can compare before spending anything. The OpenRouter key itself is free.

Does this site see my key?

No. Your key stays in your browser; we never receive it.