Diff checker for Next.js & Supabase code. In your browser.
Compare text, configuration and migration snippets side by side or inline, with line numbers and a local diff export. No uploads — free, no sign-up.
Loading the tool…
Exact line comparison only, bounded for browser responsiveness. Review migrations in your own test environment.
How to use
- Paste the original and changed text or code. Whitespace and line endings remain significant.
- Choose Compare text, then switch between Side by side and Inline without recomputing.
- Review additions, removals and unchanged lines; copy or download the line diff. Use JSON diff for structured JSON changes.
Frequently asked questions
Is this free, and does anything leave my browser?
Free, no sign-up. Inputs and outputs stay in your browser, with no processing endpoint or upload. Copy and download are local. Usage events contain only a fixed tool name and action, never your data.
Does it compare code semantically?
No. It compares exact lines using longest common subsequence. It does not run code, parse syntax or prove that a migration is safe. JSON diff is available separately for structural JSON comparison.
What is the difference between the two views?
Side by side pairs removed and added lines within each changed block and keeps original and new line numbers. Inline shows both sequences in one column, using plus and minus markers as well as color.
Is whitespace ignored?
No. Spaces, tabs, carriage returns and final newlines can change the diff. The export preserves text. Visually identical lines may differ in invisible characters, so check line endings in your editor.
Can I compare large files?
Use a combined sample under 200 KB, at most 1,500 lines per side and at most two million line comparisons. These limits bound browser memory and CPU. Split larger files into sections.
Is the export a git patch?
It is a line diff with leading space, plus and minus markers. It includes no filenames or patch hunk headers and should be read as a comparison report, not applied with git apply.
Related tools
All free toolsBase64 encode / decode
Encode and decode Base64 text and files, create image data URIs and use URL-safe encoding. Recognize JSON and JWTs. Free, no sign-up, browser only.
Markdown editor & table generator
Edit Markdown with a live preview, create tables and start from README.md, AGENTS.md, CLAUDE.md or llms.txt templates. Free, no sign-up, browser only.
Unix timestamp converter
Convert epoch seconds, milliseconds and ISO dates in your browser. Inspect time zones and PostgreSQL timestamptz for Next.js + Supabase. Free, no sign-up.