GPT-ChatDIY

GPT-ChatDIY is a browser extension for people who prefer to talk to ChatGPT through their own API key instead of the standard web interface. You install it in Chrome, add the API key you generated from your OpenAI account, and get a compact chat panel with a persistent local history. Version 1.4 added a dictionary-based privacy check on top of the earlier regex-based detection, so you can register your own sensitive words and be alerted whenever a prompt contains one.

The extension keeps history in local browser storage only. According to the developer, no personal data is transmitted back to them, and the project's source code is published on GitHub for inspection. It ships with English and Japanese interface languages, a history download option, and a simple cost estimation view so you can keep an eye on how much your API usage is roughly costing.

The roadmap published on the store page mentions token-accurate cost calculation, masking of detected personal information, prompt suggestions for common scenarios, direct CSV download, more interface languages, and multi-turn conversation memory. Until those land, the tool is deliberately minimal: a personal, private client for the OpenAI API rather than a full ChatGPT replacement.