I built Specmark to solve a friction point in AI-assisted development: reviewing specs before handing them to a coding agent. When you want to give feedback on a markdown spec, it's tedious to reference specific sections — "in the auth part..." requires extra typing and context. Specmark lets you paste markdown, highlight and annotate it inline, then copy all your comments with line numbers and quoted text to feed back to the LLM.

More on why I built it and what I learned: https://jlbrooks.tech/2026-02-01-launching-specmark/