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About this tool
Strip stray markdown, smart quotes and invisible characters from text before pasting it into an AI model.
The Prompt Markdown Cleaner strips stray markdown syntax, straightens smart quotes and deletes invisible Unicode characters from text before you paste it into an AI model. It maps typographic punctuation (U+2018–U+201D curly quotes, em dashes, ellipses, non-breaking spaces) back to plain ASCII and removes zero-width spaces, BOMs and soft hyphens that ride along in copy-paste. It runs entirely in the browser, for anyone who moves text between Word, Google Docs, chat apps and an LLM all day.
Open Prompt Markdown Cleaner on AltFTool — it loads instantly in your browser.
Paste or type the text you're working with.
Choose how it should be transformed or analyzed.
Copy the finished text into your document or post.
Invisible characters, smart punctuation, markdown syntax and whitespace can each be toggled separately.
See exactly how many characters each pass fixed, so nothing is altered silently.
All cleaning happens locally in the browser; the text is never uploaded.
Word processors autocorrect straight ASCII quotes to typographic 'smart' quotes (Unicode U+2018/U+2019 and U+201C/U+201D) as you type. When that text is pasted into a prompt, code sample or config file, the curly characters are different code points from ' and ", which can break string matching and code. This tool maps them back to their ASCII equivalents.
Zero-width characters such as the zero-width space (U+200B), zero-width joiner (U+200D) and byte-order mark (U+FEFF) occupy no visible width but are real characters in the string. They commonly arrive via copy-paste from web pages and can silently break exact-match instructions, identifiers and JSON. The cleaner deletes them and reports how many it found.
No. Fenced code blocks keep their inner code — only the ``` fence markers and language tag are removed. Links are converted to 'text (url)' so the destination is preserved, and images are reduced to their alt text.
No. The cleaning is a pure string transformation that runs in your browser tab; nothing is transmitted or stored. You can verify this by loading the page and then going offline — the tool keeps working.