Text Diff Checker — Compare Two Texts Online
Compare two blocks of text and see line-by-line differences highlighted instantly — additions and deletions color-coded. Free, client-side diff tool.
🔒 100% Client-Side Processing
Your data is processed entirely in your browser and never transmitted to any server.
Common Use Cases
Config change review
Paste the current production config next to the proposed one before a deploy and see exactly which lines changed — no git required for files that live outside version control.
API response comparison
Compare a response from staging against production to isolate what a backend change actually altered in the payload.
Document revision checks
Verify what a colleague changed between two versions of a contract, policy, or SQL schema dump when no tracked-changes history exists.
Frequently Asked Questions
- How does the diff checker compare the texts?
- It runs a longest-common-subsequence (LCS) diff over whole lines — the same family of algorithm behind git diff. Unchanged lines stay neutral, lines only in the original are marked removed (−), and lines only in the changed version are marked added (+).
- Why does a one-character edit show as a removed line plus an added line?
- The comparison is line-granular: any line that differs by even one character counts as a different line, so it appears as the old line removed and the new line added. This keeps the output unambiguous for code review and config comparison.
- What can I compare with a text diff?
- Two versions of a config file before deploying, API responses before and after a change, contract or document revisions, SQL schema dumps, and pasted code snippets — anywhere you need to spot exactly what changed between two versions.
- Does this diff checker upload my text to a server?
- No. Unlike diff tools that transmit your text to a server for processing (even ones that claim to encrypt it in transit and not store it), the comparison here runs entirely in your browser's JavaScript engine — the two texts you paste never leave your device.
- Can I compare two files instead of pasting text?
- This tool compares pasted text, not uploaded files — open the file in any text editor, copy its contents, and paste into either box. For very large files this is still fully client-side and has no upload size limit, since nothing is sent anywhere.
- Is there a version of this that understands JSON structure instead of just lines?
- Yes — the JSON Diff Checker compares two JSON objects semantically, ignoring whitespace and key order, and reports exactly which keys were added, removed, or changed instead of flagging whole lines as different.
- Is my data private when I use this tool?
- Yes. This tool runs entirely in your browser using client-side JavaScript — nothing you type is transmitted to, logged by, or stored on any server. You can safely process confidential text, tokens, or code.