Build your Diff Checker with AI in under 5 minutes

Build a diffchecker.com-style text and code comparison tool with side-by-side and unified views, line-by-line add/remove highlighting, and ignore-whitespace / ignore-case options — runs entirely in the browser, generated from a single prompt.

Hoe het werkt

Stap 1

Beschrijf je idee

Schrijf een prompt die beschrijft wat je wilt.

Stap 2

AI bouwt het

FloopFloop genereert productieklare code direct.

Stap 3

Deploy & ga live

Je project wordt gehost op een eigen subdomein in minuten.

Waarom bouwen met AI in plaats van een developer inhuren?

	FloopFloop	Traditionele developer
Tijd tot lancering	Minder dan 5 minuten	2-8 weken
Kosten	Vanaf €0	€5.000 - €50.000+
Onderhoud	Inbegrepen	Doorlopend contract

What is a diff checker?

A diff checker compares two blocks of text and shows exactly what changed between them. The genre — diffchecker.com, text-compare.com, diffnow, mergely, draftable — serves anyone who needs to spot the difference between two near-identical things: developers reviewing a snippet or a config change, writers and editors comparing two drafts of a contract or a manuscript, support engineers checking a customer's broken file against a known-good one, and students checking their work against a reference. The platonic diff tool is instant and unambiguous: paste original and changed, and the additions light up green, the deletions red, with unchanged lines kept in place so your eye goes straight to what moved. Because the comparison is pure text processing, it should run entirely in the browser — pasting a half-finished contract or a production config onto a stranger's server just to see what changed is exactly the privacy trade nobody should have to make.

Common features

Two line-numbered input panels for the original and changed text
An LCS line diff that keeps unchanged lines aligned
Side-by-side view with a central seam and a unified (+/-) view
Additions in green, deletions in red, with per-line gutters
Ignore-whitespace and ignore-case options (comparison normalised, display verbatim)
A +additions / -deletions summary
Copy-as-unified-diff for pasting into a ticket or chat
Swap, clear, and load-sample shortcuts
Last comparison remembered in localStorage
A line cap with a truncation notice so huge pastes never hang the tab

Real-world examples

Reviewing a config change

An engineer pastes the old and new versions of a YAML file, flips to unified view, copies the +/- block into the change ticket, and ships the review without leaving the browser.

Comparing two contract drafts

A founder pastes the counterparty's redline against their own version, sees the three clauses that actually changed highlighted in red and green, and replies in minutes instead of re-reading ten pages.

Debugging a customer's broken file

A support engineer diffs the customer's config against the known-good template, spots the one transposed line, and pastes the fix back — all on a private subdomain with nothing uploaded.

Why FloopFloop fits diff checker projects

The best diff tools are dead simple and a little opinionated, and the hosted ones make their money by either showing you ads or holding the good features behind a wall. FloopFloop ships the diff checker you actually want: side-by-side or unified, the theme you prefer, the ignore-rules that match your work, all on your own domain with nothing uploaded. The 'code-review desk' that ships by default reads like a pull-request review rather than a SaaS landing page — and the whole look is one prompt away from being whatever suits you.

Probeer deze prompts

Kopieer een prompt en plak deze in FloopFloop om te beginnen.

Build a diff checker that compares two blocks of text or code. Two line-numbered input panels, then a result that highlights differences line by line using a longest-common-subsequence diff so unchanged lines stay aligned — additions in green, deletions in red. Offer a side-by-side view and a unified (+/-) view, ignore-whitespace and ignore-case toggles, a +adds/-removes stat, and a copy-as-unified-diff button. Persist the last comparison to localStorage. Visual: a clean light 'code-review desk' with a central seam between the two panels and monospace code.

Create a text-compare tool like diffchecker.com or text-compare.com. Paste original and changed text, see the differences highlighted instantly, swap the two sides with one click, and clear both. Keep it entirely client-side — nothing the user pastes should leave the browser.

Build a code diff viewer for reviewing snippets. Unified view with +/- gutters and line numbers from both sides, syntax-neutral monospace rendering, and an ignore-whitespace option so reindentation doesn't drown the real changes. Add a GitHub-dark theme variant.

Build a side-by-side document comparison tool. Align matching lines, render inserted lines on the right with a blank cell opposite and removed lines on the left, show a summary of how many lines were added and removed, and cap very large pastes so the tab never hangs.

Veelgestelde vragen

How is this different from diffchecker.com or text-compare.com?

Those hosted tools work, but free tiers paste your text onto someone else's server (sometimes with size limits or ads), and you can't change how they look or behave. The version FloopFloop generates runs the diff entirely in your browser, keeps your last comparison in localStorage only, and is yours to restyle, extend with a word-level diff, or wire to your repo — no quota, no telemetry.

What diff algorithm does it use?

A longest-common-subsequence (LCS) line diff — the same family git diff uses. It finds the longest run of shared lines and only flags the real insertions and deletions, so a one-line change in the middle of a file doesn't mark everything after it as different the way a naive line-by-line compare would.

Is my text uploaded anywhere?

No. Both inputs, the comparison, and the rendered result stay in the browser; only your last comparison is saved, and only to this device's localStorage. The single outbound surface is the /api/health probe.

Does it handle large files?

It diffs up to a few thousand lines per side instantly and caps pathological pastes with a truncation notice so a multi-megabyte dump can't lock up the tab. Ask the AI to raise the cap or add a Web Worker if you routinely compare very large files.

Can it do word-level or JSON-aware diffing?

The default is a line diff. Ask the AI to add an intra-line word diff (highlighting the changed words within a modified line) or a JSON-aware mode that normalises key order before comparing — both are templated additions, not rewrites.

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