Lex

Lex is an AI writing assistant built into its own document editor, for newsletter authors, marketers, academics and small teams; free plan and per-user Pro.

Lex brings an editor's feedback, rewrites and research to the draft itself, so nothing has to be pasted into a separate chat window. Lex, Inc., an independent company led by chief executive Nathan Baschez, builds it and sells it as its only product. Writing, sharing and collaborating on documents work on every account. The AI tools wait beside the text until the writer calls them. Ask Lex is the chat panel, used to brainstorm, research, outline and generate first drafts, with files and links attached as context. Checks run line edits on demand, starting from pre-loaded grammar and brevity checks that explain each fix, and users can build custom Checks for their own rules. Style Guides hold writing samples and instructions, so drafts and edits come back in the writer's voice. The Rewrite tool rephrases clunky sentences, and the +++ command continues the text. Rewind scrubs back through earlier states, named Versions save snapshots with their comments, and finished work exports to Word, PDF, Markdown, HTML or LaTeX. Lex is aimed at people whose work is mostly words: newsletter writers and Substack authors, marketers drafting customer copy, academics, journalists, founders and novelists. Solo writers use it alone, and a small team can share folders, prompts and Context Tags. It is sold per user. A free account carries daily caps on the AI, while Lex Pro, billed monthly or annually, adds premium models from OpenAI and Anthropic and a monthly allowance of AI credits. Groups that collaborate heavily add Lex Teams for unlimited use of team folders, and nonprofits, students and academics can ask for a discount. Newsletter issues, academic papers, customer copy, important emails and fiction are the documents Lex is built around. Knowledge Bases give the assistant background it keeps across every document, for more relevant, personal help. Documents can be set to Spanish, Portuguese, French, Italian, German or Korean as well as English. Kit users connect their newsletter account to Lex for the writing side of each issue, and developers reach the same documents through a simple API. For someone who wants an editor's notes on every draft before it goes out, Lex keeps that review inside the document.