Erse
Batch Text Editor for Mac & iPad
Erse is a native app for transforming text files in bulk. Drop in any number of .txt, .csv, .tsv, .log, or Markdown files, build a stack of transformation rules, watch a live side-by-side preview update as you work, then export clean copies — all at once, without writing a single line of code.
Built for Real Text Work
Cleaning up exported CSVs before import. Normalizing log files for analysis. Renumbering, reformatting, and tidying lists. Bulk-editing config files, prose drafts, or data dumps. Merging many documents into one. Erse handles it without the command line, regular- expression cheat sheets, or a throwaway script.
Seven Rules. One Stack.
Add as many rules as you need, in any order. Erse applies them top-to-bottom to every file in your batch.
Edit Text
- Find & Replace — literal, wildcard (*, ?, {number}, {text}), or full regular expressions with backreferences, case-sensitive or not
- Change Case — UPPERCASE, lowercase, Title Case, Sentence case, camelCase, PascalCase, snake_case, kebab-case, and CONSTANT_CASE
- Trim — strip leading/trailing whitespace, collapse internal runs, remove or collapse blank lines, convert tabs to spaces
- Insert — add a prefix or suffix, with optional separators and auto line numbering
Shape Lines
- Strip / Filter — keep or remove lines matching a pattern, drop blank lines, or remove duplicates
- Sort — ascending or descending, alphabetical, case-sensitive, numeric, or by length; sort by CSV column; pin the header row
Merge
- Combine — append or prepend the contents of another document, with configurable joiners and CSV-aware row merging
Scope Each Rule
Apply any rule to the whole document, to each line individually, or — for CSV and TSV files — to each field, so a transform touches exactly the text you mean it to.
Live Preview — Always Watching
A dedicated preview panel shows the exact result of your full rule stack on the selected file, updating in real time as you tweak any setting. Flip to a side-by-side original-versus-transformed view to see precisely what changed. Large files are previewed safely without choking on size.
Encoding-Safe, Round-Trip Clean
Erse detects each file's text encoding, byte-order mark, and line endings (LF, CRLF, or CR) and preserves them on export, so an empty rule stack writes a byte-identical copy. When a transform needs characters the original encoding can't hold, Erse promotes the file to UTF-8 and tells you.
Built-In Presets
Jump-start common workflows: Tidy Whitespace, Sort & Dedupe Lines, and lowercase Everything. Or save any rule stack as your own named preset for instant reuse across batches.
Save Copies by Default — Undo the Whole Batch
Erse saves transformed copies (with a “-erse” suffix) so your sources stay untouched, or overwrite on purpose when you choose. Conflicts are yours to resolve — keep both, overwrite, or skip. Made a mistake? Undo moves every file from the last run to the Trash and restores anything it overwrote, in one action.
Native and Private
Erse is a native app built in SwiftUI for Mac and iPad. All processing happens on your device — no cloud uploads, no subscription, no account required. Your files never leave your machine.
Privacy
Erse collects no data and contains no telemetry of any kind. Read the full privacy policy. · Help & User Guide