Snap your prose into clean, diff-friendly lines

A fast, format-aware semantic line break formatter for academic papers and collaborative writing.

View on GitHub Documentation
See it in action

One sentence, one line

Traditional wrapping hides changes in paragraph-wide diffs. Snapper breaks at sentence boundaries so every edit shows exactly what changed.

Before (traditional wrapping) We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. This approach dramatically reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements.
After (snapper) We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. This approach dramatically reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements.
Without snapper: change one word, diff shows entire paragraph --- a/paper.org +++ b/paper.org @@ -1,3 +1,3 @@ -We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. This approach dramatically reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements. +We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. This approach significantly reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements.
With snapper: same change, diff shows one line --- a/paper.org +++ b/paper.org @@ -1,3 +1,3 @@ We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. -This approach dramatically reduces noise in version control diffs when multiple authors collaborate on a manuscript. +This approach significantly reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements.
snapper sdiff compares files at the sentence level. Whitespace reflow produces zero diff -- only actual content changes appear.
Same one-word change, but diffed at sentence level: $ snapper sdiff paper_v1.org paper_v2.org @@ -1,3 +1,3 @@ We present a method for formatting prose documents with semantic line breaks, where each sentence occupies its own line. -This approach dramatically reduces noise in version control diffs when multiple authors collaborate on a manuscript. +This approach significantly reduces noise in version control diffs when multiple authors collaborate on a manuscript. Our tool handles LaTeX, Org-mode, Markdown, and plaintext with format-aware parsing that preserves structural elements.
Paragraph reflow (rewrapping the same text) produces no diff at all: $ snapper sdiff wrapped_at_80.org semantic_breaks.org No sentence-level differences.
Features

Built for academic workflows

Everything you need to adopt semantic line breaks across your paper writing toolchain.

Format-aware parsing

Understands Org-mode, LaTeX, Markdown, RST, and plaintext. Code blocks, math environments, tables, directives, and drawers pass through untouched.

Abbreviation-aware

Handles Dr., Fig., Eq., e.g., i.e., et al. and 80+ more. Add project-specific abbreviations via .snapperrc.toml.

Pre-commit hook

Ships with .pre-commit-hooks.yaml. Enforce semantic line breaks automatically on every commit across your team.

Editor integration

Stdin/stdout interface works with Emacs Apheleia, vim, and any editor that supports external formatters. Format on save.

Vale style package

Bundled vale rules flag lines with multiple sentences in your editor. Use --check for precise CI enforcement.

Git smudge/clean filter

Auto-format on commit, transparent to collaborators. Add to .gitattributes and formatting happens silently.

Neural sentence detection

Optional ML-based splitting via nnsplit for 9 languages. Use --neural --lang de for non-English text where rules fall short.

Skip regions with pragmas

Mark hand-formatted text with snapper:off / snapper:on comments. Poetry, aligned text, and ASCII art pass through untouched.

One-command setup

snapper init detects your formats and generates config, pre-commit hooks, gitattributes, and editor snippets.

Get started

Install in seconds

Cargo
# pre-built binary (fastest)
cargo binstall snapper-fmt
# or compile from source
cargo install snapper-fmt
Shell / Homebrew
# one-liner (Linux/macOS)
curl -LsSf https://github.com/TurtleTech-ehf/snapper/releases/latest/download/snapper-fmt-installer.sh | sh
# or Homebrew
brew install TurtleTech-ehf/tap/snapper-fmt
pip / Nix
# pip (with maturin wheels)
pip install snapper-fmt
# Nix
nix build github:TurtleTech-ehf/snapper
Pre-commit
# .pre-commit-config.yaml
- repo: https://github.com/TurtleTech-ehf/snapper
  rev: v0.3.2
  hooks:
    - id: snapper