{"slug": "i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it", "title": "I Built a LaTeXdiff Online tool – using Claude Code (Reddit users Loved it)", "summary": "A developer built a free online LaTeXdiff tool using Claude Code, allowing users to compare .tex files without installing Perl or using a terminal. The tool, which gained popularity on Reddit, addresses the difficulty of installing latexdiff on Windows and the cost of Overleaf's Track Changes feature. It marks additions in blue and deletions in red strikethrough, supporting various options for journals and co-author workflows.", "body_md": "[5.0 · 500+ Projects Delivered](/cdn-cgi/l/email-protection#8be3eee7fba5ffe3eee7eaffeef3e7eae9cbece6eae2e7a5e8e4e6)\n\n# LaTeXdiff Online\n\nFree Tool, No Perl install, No Terminal\n\nUse LaTexdiff Online to compare two .tex files and instantly see what changed. Paste your original and revised LaTeX files, then generate a marked-up version for journals, supervisors, or co-authors.\n\n## How it works\n\n`\\DIFadd{...}`\n\naround additions and `\\DIFdel{...}`\n\naround deletions. Compile it with pdflatex to see additions in blue and deletions in red strikethrough.## Options explained\n\n`type`\n\nHow additions are marked. UNDERLINE wavy-underlines them, CHANGEBAR puts a vertical bar in the margin, CFONT uses a different font. Switch to CHANGEBAR if your journal asks for marginal change marks rather than inline markup.`UNDERLINE`\n\ndefault`subtype`\n\nHow deletions are marked. COLOR uses red strikethrough, FONTSTRIKE strikes through without colour, SAFE is the most conservative. Use SAFE if `\\DIFdel`\n\nis breaking your document, since some journal classes redefine commands that conflict.`COLOR`\n\ndefault`floattype`\n\nHow figures and tables are handled. IDENTICAL leaves them alone unless content changed, FLOATSAFE wraps every float in protective commands. Use FLOATSAFE if floats are silently disappearing in the diffed output.`IDENTICAL`\n\ndefault`math-markup`\n\nHow equations are diffed. coarse marks any changed equation as one block, fine diffs inside the equation, whole always marks the whole equation, off ignores math changes. Use fine to see exactly which symbols changed, though it is fragile.`coarse`\n\ndefault## Limitation\n\n`\\input{}`\n\nor `\\include{}`\n\nto pull in chapters, the tool will not flatten them automatically. Inline everything first, or wait for the multi-file version.`ulem`\n\npackage.## What latexdiff actually does\n\n### Marks every change\n\n`latexdiff`\n\nis a Perl script that compares two LaTeX source files and produces a third LaTeX file with the changes marked up using two macros: `\\DIFadd{...}`\n\nfor insertions and `\\DIFdel{...}`\n\nfor deletions. When you compile that third file with pdflatex, the additions appear in blue and the deletions appear in red strikethrough. The `ulem`\n\npackage handles the strikethrough.\n\n### It understands LaTeX\n\nIt is not a text diff. A plain `diff`\n\ntool would compare your files line by line and miss the LaTeX structure entirely — it would flag a renamed `\\section{}`\n\nas a complete rewrite even if you only changed one word. `latexdiff`\n\nunderstands LaTeX. It diffs paragraphs, sentences, equations, and citations as separate units, and it leaves the document compilable on the other side.\n\n### Why researchers use it\n\nThis matters because most researchers use latexdiff for one of three reasons: tracking what changed between drafts when working with co-authors, generating a revision file for journal resubmission, or sanity-checking changes during a thesis revision pass. Many journals require authors to upload both a clean manuscript and a marked-up revision showing all changes — `latexdiff`\n\nis the standard way to produce that second file. None of these workflows work with a generic text diff.\n\n### Why run it online\n\nThe catch is installation. `latexdiff`\n\nships with TeX Live and MiKTeX on most Linux and Mac setups, but Windows users almost always hit a wall — `latexdiff`\n\nis a Perl script, and Perl is not preinstalled on Windows. You end up installing Strawberry Perl, then pointing TeX Live at it, then dealing with path issues. Overleaf users hit a different wall: `latexdiff`\n\nis built into Overleaf's Track Changes feature, but that feature is gated behind their paid Premium plan. For a one-off comparison, neither path is worth the effort. That is the gap this tool fills — a free, online `latexdiff`\n\nthat works in any browser, with no install and no subscription.\n\n## Frequently asked questions\n\nNo. Perl runs server-side on our end. You just paste the two files and get a result.\n\nNo. `diff`\n\nis a generic text comparison tool that does not understand LaTeX structure. `latexdiff`\n\nparses the LaTeX, then diffs at the paragraph and equation level, then writes a compilable LaTeX file with markup macros. The two are not interchangeable.\n\nThe most common cause is a missing `ulem`\n\npackage on your local install. `latexdiff`\n\nadds `\\RequirePackage[normalem]{ulem}`\n\nto the diffed file's preamble — if you do not have it, the compile fails on that line. Install it from your TeX distribution and the file will compile.\n\nThe second most common cause is template incompatibility. Some journal classes (`elsarticle`\n\n, `acmart`\n\n, `sn-jnl`\n\n) redefine commands that conflict with `\\DIFadd`\n\nand `\\DIFdel`\n\n. Switch the `subtype`\n\noption to `SAFE`\n\nand try again.\n\nYes, if your Overleaf project is a single .tex file. Download both versions from Overleaf (Menu → Download → Source), open the .tex files, and paste each into the box above. The tool produces the same diff Overleaf's paid Track Changes feature would, without the subscription.\n\nFor comparing two completed file versions, yes. Overleaf's Track Changes is a live, interactive editor on the Premium plan. This tool generates a static diff of any two `.tex`\n\nfiles in seconds, free, without a subscription. If your Overleaf project uses multiple files via `\\input{}`\n\nor `\\include{}`\n\n, you currently need to flatten them first — a multi-file version of this tool is coming.\n\nYes, free. It runs on a small server-side service and serves a few thousand requests a month comfortably. No signup, no paid tier.\n\n## Need the manuscript formatted for IEEE, Springer, Elsevier, ACM, or another journal template?\n\nWe handle submission-ready LaTeX typesetting from $49. Send the source files, get back a paper that compiles cleanly and matches the journal spec.", "url": "https://wpnews.pro/news/i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it", "canonical_source": "https://thelatexlab.com/latexdiff-online/", "published_at": "2026-06-17 08:13:22+00:00", "updated_at": "2026-06-17 08:22:46.444998+00:00", "lang": "en", "topics": ["developer-tools", "ai-tools", "large-language-models"], "entities": ["Claude Code", "LaTeXdiff", "Overleaf", "Perl", "TeX Live", "MiKTeX", "Strawberry Perl", "Reddit"], "alternates": {"html": "https://wpnews.pro/news/i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it", "markdown": "https://wpnews.pro/news/i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it.md", "text": "https://wpnews.pro/news/i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it.txt", "jsonld": "https://wpnews.pro/news/i-built-a-latexdiff-online-tool-using-claude-code-reddit-users-loved-it.jsonld"}}