SecondPen.aiA writing tool with a second pen in the margin.
Write in rich text or markdown. Point at a sentence and ask. The AI edits what you chose, in place, with one undo. It never touches a line you did not pick.
No account needed to try it. Sign in to keep documents across devices.
Edits land where you point
Select any passage. Six one-click actions, or type your own instruction. The result replaces the selection, flashes so you can see it, and undoes in a single step.
Write at the cursor
Type a slash on an empty line and say what you want written. It writes only in that spot, in the voice of the document around it, and you keep editing while it works. Ask a question instead, and the answer goes to the Co-author.
An editor and a critic, always on
Two standing lists beside the draft: line edits you can apply, and the hard questions a sceptical reader would ask. Both stay current as you write, judged against your abstract, and say plainly when the piece is ready. Dismiss a note and it does not come back.
It learns to write like you
Paste something you wrote, or bring it in from a link or a file. The AI reads it once, writes a short profile of how you write, and quotes your best sentences back to itself on every request. What it writes for you sounds like you, not like it. Your voice stays with your account, apart from any one document.
Start from a format that works, then score against it
132 document formats top operators use, from a six-pager to a postmortem to a résumé to a cold email, each with its sections and guidance in place. Write an abstract or ask for a document and the editor names the format it reads like. When the draft is ready, the Critic scores it the way that format's toughest reader would, and the fixes arrive as cards.
Markdown underneath
Rich text on top, markdown as the stored form. Switch views any time. Export to Markdown, HTML, Word or PDF, and import Word and Markdown files. Nothing is locked in.