ShroomPen: BYOK AI Writing Assistant

Reply, rewrite, fix grammar and translate in any text box with your own API key: OpenRouter, OpenAI, Gemini, Claude or Ollama.

ShroomPen is an AI writing assistant that works inside the text boxes you already use. Click into a field and a small mushroom appears at its corner. Click the mushroom and a row of buttons opens next to it: • Reply: answers the message in front of you. Your rough note is the brief. • Rewrite: makes your draft clearer and more natural, with the same meaning. Hover it for Shorter, Simplify or Expand. • Fix grammar: spelling and punctuation, in the language you wrote. • Translate: into the language you pick. Select part of the text to translate just that part. Rewrite, Fix grammar and Translate appear once the field has text in it. Tell Reply what you want Hover Reply and it opens its own prompt. Add a line ("offer a refund", "ask for the order number"), press + to pick text on the page for the reply to use, or type / to add a skill such as /formal, /bullets or /email. Press Enter and the reply streams into the field as the model writes it (rich text editors get it in one piece when it is done). Press Esc to stop it and get your text back. Replies with the facts in them Context & Brain, the last button in the row, shows what the next reply will read, and you choose: the field, the current page, text you selected, other open tabs you pick, a PDF open in a tab, and the pages, notes and files saved in your Workspace. Names, order numbers and dates come from those sources instead of being guessed. Preview shows what will be sent, source by source, before you send it. The model button at the bottom switches between up to five models you keep in the menu, from any of your providers. Skills A skill is a short instruction you save once: a tone, a format, or a task with its own steps. ShroomPen comes with seven (Formal, Friendly, Concise, Bullet points, Email, One line and Summarize), and you can write your own in Settings. Type / in Reply to use one for a single reply, or turn it on for a Workspace so it applies to every Reply and Rewrite there. Workspaces A Workspace keeps one kind of writing together, such as support replies or sales emails: its tone, language and instructions, the pages, notes and text files ShroomPen reads with each reply, and its own skills. It can also use its own provider and model, whatever the model menu says. Switch Workspaces in Context & Brain, and save the tabs you picked to a Workspace to use them again. The mushroom takes the color of the Workspace you are in. Settings Settings opens in a full tab: Models, Providers, Skills, Workspaces, and Privacy & data. A guided setup walks you through connecting a provider: choose a local model, a free model, a free-tier provider or a paid one, connect it, and pick a model. Model lists show only models that write text, and where the provider publishes prices (OpenRouter does), an estimated cost per reply. The writing panel For anything longer, press Ctrl+Q (you can change the shortcut), click the toolbar button, or right-click and choose Open ShroomPen. The writing panel takes a plain instruction, lets you edit the result, and then copies it or inserts it into the page. Bring your own key (BYOK) ShroomPen runs on your own AI provider account: • OpenRouter: sign in once, no key to copy. One account covers many models, free ones included. • OpenAI or Gemini: paste your API key. • A local model in Ollama or LM Studio: no key, no cost, and requests stay on your computer. • Any other endpoint that accepts OpenAI-format requests. More direct providers are listed in the settings. ShroomPen itself is free. There is no ShroomPen account and no subscription. You pay your provider for what you use, or nothing with a local model. Privacy, in short • There is no ShroomPen server. Requests go straight from your browser to the provider you set up, over HTTPS. Plain HTTP is allowed only for a model on your own computer. • Page and field text is sent to your provider only when you start a request, and only from the sources you leave on. A field changes only when you click an action or Insert. • Password, payment card and one-time-code fields are skipped. You can switch ShroomPen off for any site. • The extension has no analytics, telemetry or ads. The ShroomPen website counts page views in aggregate; the extension sends it nothing. • Settings and API keys are stored in your browser profile. ShroomPen does not add its own encryption to them, and each key is sent only to its own provider. • Before first use, ShroomPen shows what it reads and where it goes, and waits for your OK. Settings > Privacy & data > Clear local data removes what it stored. Privacy policy: https://shroompen.com/privacy Setup guides and help: https://shroompen.com