Free Text Diff Tool - Compare Code & Documents

Common algorithms: (1) Myers diff: most common, used by Git, balanced accuracy/performance. (2) Patience diff: better for code, handles rearrangements well. (3) Histogram diff: variant of Patience, faster. (4) Word-level diff: compares words not lines, better for prose. (5) Character-level diff: most granular, shows exact character changes. Myers for general use, Patience for code with moved blocks, word-level for documents, character-level for detailed analysis. Trade-offs: accuracy vs speed. This tool uses optimized Myers algorithm with word-level highlighting for precise comparison.

Whitespace options: (1) Ignore all whitespace: treats spaces, tabs, newlines as identical. (2) Ignore leading/trailing whitespace: only ignore at line edges. (3) Ignore whitespace changes: treats multiple spaces as one. (4) Case-insensitive: treats uppercase/lowercase as same. Use cases: comparing code after reformatting, ignoring indentation changes, comparing across different editors, focusing on content not style. Command-line: diff -w (ignore whitespace), diff -i (case-insensitive). This tool offers toggle options for each whitespace handling mode. Useful for finding actual content changes.

Split (side-by-side): shows both files in parallel columns, left = original, right = modified, visual alignment, easier to read. Best for: small files, quick visual comparison, presentations. Unified (inline): single column with +/- markers, + for additions, - for deletions, context lines unmarked, more compact. Best for: large files, patches, email, version control. Context diff: shows surrounding lines for context. Patch format: unified diff that can be applied with patch command. This tool defaults to split view for clarity, offers unified export for version control integration.

Code review workflow: (1) Compare your branch vs main branch code. (2) Review additions (new functionality), deletions (removed code), modifications (bug fixes). (3) Check for: breaking changes, code quality, test coverage, documentation updates. (4) Leave comments on specific lines. (5) Request changes or approve. Share diffs: export as text or HTML, create patch file for applying changes, share link (if tool supports), screenshot for discussions. Integration: most version control (Git, SVN) has built-in diff, GitHub/GitLab show diffs in pull requests. This tool complements version control for ad-hoc comparisons.

Plain text diff works but not ideal for structured data. Better approaches: (1) JSON diff: special tools compare structure, ignore formatting, highlight value changes, handle nested objects. (2) XML diff: compare DOM structure, ignore attribute order, namespace-aware. (3) Semantic diff: understand language syntax, ignore comments/whitespace. Tools: jq for JSON, xmldiff for XML, language-specific parsers. Formatting first: pretty-print JSON/XML before comparing for better alignment. This tool handles text-based comparison; for complex JSON/XML, use specialized tools or format consistently first.

Patch file: unified diff format that can apply changes to original file. Create patch: diff -u original.txt modified.txt > changes.patch. Apply patch: patch original.txt < changes.patch. Patch format: --- original.txt, +++ modified.txt, @@ -1,4 +1,4 @@ (hunk header), - old lines, + new lines. Reverse patch: patch -R to undo changes. Dry run: patch --dry-run to test without applying. Multiple files: diff -ruN old_dir/ new_dir/ > changes.patch. Git: git diff > changes.patch, git apply changes.patch. This tool can export unified diff format for creating patches.

Large files: use command-line tools (diff, git diff) for better performance, browsers may freeze on files >10MB, consider splitting into chunks, use binary diff tools for non-text files. Directory comparison: diff -r dir1/ dir2/ compares recursively, tools like Meld, Beyond Compare for GUI, identify added/removed files, compare file sizes/timestamps. Optimization: filter files (ignore .git, node_modules), compare hashes first (MD5/SHA256), use incremental comparison, parallel processing for speed. This browser-based tool best for files under 1MB; use desktop tools for larger comparisons.