OnlineDeveloperTool
Text & Data

Diff Checker Online

Paste two versions of a text and see what was added or removed, line by line.

Updated

This tool runs in your browser. No account or signup is required.

Common Diff Checker tasks

Developers typically reach for this page when they need to compare two texts online; compare code and configuration files; find differences between two versions. The tool is built for quick, practical work rather than a generic demo.

What matters in a diff checker workflow

When developers compare online tools for this job, the useful capabilities tend to center on side-by-side/unified, word/char diff, ignore rules, files/download. This page keeps those practical needs in mind while linking to related tools when a different workflow is a better fit.

What is Diff Checker?

Diff Checker compares two blocks of text line by line and marks lines that were added (+), removed (-) or unchanged.

What problem does it solve?

When two configs, responses or snippets look the same but behave differently, reading them side by side by eye misses things.

How to use Diff Checker

  1. Paste the original text on one side and the changed text on the other.
  2. Press compare.
  3. Read the result and copy it if you need to share it.

Example

Original vs changed

host=localhost
port=80

host=localhost
port=8080

Result

  host=localhost
- port=80
+ port=8080

What you can do with Diff Checker

  • Diff checker online
  • Compare two texts
  • Find differences between two files

Common use cases

  • Spotting what changed between two config files
  • Comparing an expected and an actual API response
  • Checking edits before pasting them back

Related developer tasks

  • Diff checker online
  • Compare two texts
  • Find differences between two files

Diff checker example

Original:      Modified:
name: api      name: api
port: 80       port: 8080

// result
  name: api
- port: 80
+ port: 8080

How the comparison works

  • It compares the two texts line by line. Changed lines show as one removed line and one added line.
  • Removed lines are red, added lines are green and unchanged lines are grey.
  • Copy diff copies a plain-text version with + and - prefixes.
  • It does not highlight changes inside a line.

Format first for cleaner diffs: JSON Formatter, YAML Formatter, XML Formatter

Diff Checker FAQ

Is the comparison by line or by character?

By line.

Is my data sent to a server?

The processing runs in your browser, so what you paste into the tool is not uploaded for processing. As with any tool, avoid pasting live secrets you cannot afford to leak.

How do I compare two JSON files?

Format both with the JSON Formatter so each key is on its own line, then paste them into the two boxes.

Looking for something else? Browse all developer tools.

onlinedevelopertool.com is a collection of 54 free, browser-based utilities for the small jobs that interrupt real work: formatting a JSON response, decoding a token, converting a timestamp, generating a UUID or checking a hash. Each tool has its own page with a short explanation, a worked example and answers to common questions, so you can use it and learn what it does at the same time.

There is no account to create and nothing to install. Tools run in your browser, so the text you paste is processed on your own device. The one exception is the Website Status Checker, which sends a request from your browser to the address you enter.

Three steps: paste your input, click the tool, copy the result, all inside your browser
Popular developer utilities: JWT decoder, UUID generator, Base64 decoder, SHA-256 hash, regex tester and timestamp converter

What you can do here

  • JSON Tools

    Format, validate, beautify and minify JSON, generate C#, TypeScript, Java, Python, Go, PHP and Kotlin models from it, or convert between JSON, YAML and CSV.

  • Encoders & Decoders

    URL, Base64 and HTML encoding and decoding, plus a JWT decoder for reading token claims.

  • Generators & Hashes

    Generate UUIDs and JWTs, validate UUIDs, and create MD5, SHA-256 and SHA-512 hashes.

  • Web Tools

    Timestamps, color codes, query strings and cron expressions - the small things web work keeps throwing at you.

  • Text & Data

    Format XML and YAML, count text, change case, make slugs, test regex, diff two texts and convert number bases.

  • Website Checking

    Check whether a website or URL is reachable from your browser.

Quick developer reference

  • JSON

    Keys and strings must use double quotes, and trailing commas and comments are not allowed. Those are the three most common reasons a payload fails to parse.

    Validate JSON

  • JWT

    A JSON Web Token is three Base64URL parts joined by dots: header, payload and signature. Decoding shows the claims but does not prove the token is genuine; only signature verification does.

    Decode a JWT

  • Base64

    Base64 is an encoding, not encryption. Anyone can reverse it, and it makes data roughly one third larger, so never use it to hide secrets.

    Decode Base64

  • UUID

    A version 4 UUID is made of random bits and written as 8-4-4-4-12 hexadecimal characters. Collisions are astronomically unlikely, which is why they work well as identifiers.

    Generate a UUID

  • Timestamps

    A Unix timestamp counts time since 1 January 1970 UTC. Ten digits usually means seconds and thirteen digits usually means milliseconds.

    Convert a timestamp

  • Hashes

    MD5 is fine for quick checksums but is not safe for security. Prefer SHA-256 or SHA-512, and remember that hashing is one-way and is not encryption.

    Create a SHA-256 hash

Missing a tool you need? Visit the contact page and tell us what you reach for most often. You can also browse every tool or read the About page to see how the site is built and what it does with your data.