GPT-Prompter is a Chrome extension developed by giorgiosilvidev that allows users to send fast and custom prompts to OpenAI's GPT-3, GPT-4, and ChatGPT API directly from any webpage. With this extension, users can ensure the lowest cost for using GPT by querying the API directly, eliminating the need for a middleman.

To use GPT-Prompter, users simply need to click on the extension icon and insert their API Key from OpenAI. They can then select text on a web page and right-click to access the context menu and choose a prompt. The extension also allows for customization of prompts, with the keyword #TEXT# being replaced with the selected text from the webpage.

Multiple models with different capabilities and costs are available from OpenAI, including gpt-4, gpt-3.5-turbo, text-davinci-003/2, babbage, curie, and ada. Users can access and search through the history of their prompts and save them as JSON files.

GPT-Prompter is an open-source project available on GitHub, and a complete guide on how to use it can be found on the official website.