Diff Tools is a standalone, local-first application in the add·ideas Toolbox. Inputs are processed through the shared cancellable disposable-worker protocol, with an algorithm budget and a 15-second hard worker deadline, and are never uploaded by the application.

Version 0.2 scope

Text diff by line, word, Unicode code point or grapheme cluster, with exact LF, CRLF, CR and final-newline state.
Explicit text comparison rules for case, whitespace, line endings, final newline and Unicode normalization. Normalized differences stay visible.
Semantic JSON comparison with duplicate-key rejection, exact decimal numbers, object-order reporting and RFC 6902 output when representable.
Namespace-aware XML comparison with visible prefix, attribute-order, comment, whitespace and CDATA normalization. DOCTYPE, entity declarations and XInclude are rejected.
CSV and TSV comparison by one or more unique key columns, including duplicate-key diagnostics, string-preserving fields and visible column/row order changes.
Build deterministic relative-path directory manifests with local SHA-256 hashing, bounded two-file concurrency and conservative collision checks; export/import manifests and compare them without retaining file contents.
Perform a bounded, line-preserving three-way text merge from base/ours/theirs, with non-overlapping edits combined and explicit ours/base/theirs markers plus a JSON report for every conflict.
Unified and side-by-side views, an exact unified text patch and a portable, versioned JSON report.
Stable-last-result interaction: invalid or unfinished input does not blank the previous successful result.

This version does not interpret images, binary documents or archives. Directory comparison is content-digest based and cannot represent empty directories because browser directory selection exposes files only. Three-way merge is textual rather than a semantic JSON/XML merge.

Safety limits

Each ordinary or merge input is limited to 8 MiB and 4 million characters. Directory manifests are limited to 5,000 files, 512 MiB total, 256 MiB per file, 4,096-character relative paths and two concurrent hashes. Parsing and output also have explicit row, cell, token, node, nesting, edit-count, conflict-count, time and display limits. Imported values are rendered as React text nodes; parser-provided HTML is never inserted. See privacy and security.

Development

Requires Node.js 22 and npm 11.

npm ci
npm run check
npm run test:browser

The browser suite builds and serves the app below /deep/nested/diff/, blocks external requests, checks CSP and immutable worker assets, and runs on Chromium and Firefox.

Release

npm run release:artifact

This creates deterministic release/diff-tools-0.2.0.zip and .sha256 files after all validation gates pass.

Licence

GPL-3.0-or-later. Runtime dependencies retain their own licences; see third-party notices.