DevBolt
Processed in your browser. Your data never leaves your device.

How do I compare two texts and find differences online?

Paste your original text on the left and modified text on the right, then click Compare. The tool highlights added, removed, and changed lines with color coding. You can switch between inline and side-by-side views. All comparison runs locally in your browser.

Compare two code snippets
Input
Old: const x = 5;
New: const x = 10;
Output
- const x = 5;
+ const x = 10;
  1 line changed
← Back to tools

Diff Checker

Compare two blocks of text and see the differences highlighted.

Tips & Best Practices

Pro Tip

Ignore whitespace changes to focus on real differences

Reformatting code (indentation, trailing spaces, line endings) creates massive diffs that hide actual logic changes. Most diff tools have a 'ignore whitespace' option. In git: git diff -w ignores all whitespace, git diff -b ignores changes in amount of whitespace.

Common Pitfall

Line-ending differences create false diffs

Windows uses CRLF (\r\n), Unix/Mac uses LF (\n). If two files differ only in line endings, every line shows as changed. Set up .gitattributes with '* text=auto' to normalize line endings. In diff tools, use the 'ignore line endings' option to see real changes.

Real-World Example

Side-by-side vs unified diff: choose by context

Unified diff (default in git) shows changes with +/- prefixes and surrounding context — best for code review in terminals and pull requests. Side-by-side diff places old and new versions in parallel columns — better for comparing configuration files or spotting moved blocks of code.

Pro Tip

Use structural diff for JSON and YAML

Text diff treats JSON key reordering as a change, but JSON objects are unordered by spec. A structural diff (like DevBolt's JSON Diff tool) compares by key paths and values, ignoring key order and formatting differences. This eliminates noise when comparing API responses or config files.

Frequently Asked Questions

How do I compare two text files online?
Paste the original text in the left panel and the modified text in the right panel. DevBolt's Diff Checker instantly highlights additions in green, deletions in red, and unchanged lines in the default color. The tool shows line-by-line differences with line numbers for easy reference. It works with any text content — code, configuration files, log output, prose, CSV data, or API responses. Everything runs client-side so your data stays private. For large files, the diff algorithm efficiently handles thousands of lines.
What algorithm does a diff checker use?
Most diff tools use a variation of the Myers diff algorithm, which finds the shortest edit script (minimum number of insertions and deletions) to transform one text into another. It works by computing the longest common subsequence (LCS) between two inputs and representing everything else as additions or deletions. The algorithm runs in O(ND) time where N is the total length and D is the number of differences — it is fast when texts are similar. More advanced tools add a patience diff refinement that produces more human-readable results by anchoring on unique matching lines.
Can I compare JSON or code files with a diff checker?
Yes, a diff checker works with any text format including JSON, JavaScript, Python, YAML, SQL, HTML, CSS, and more. For JSON specifically, consider using DevBolt's dedicated JSON Diff tool which understands JSON structure and shows semantic differences (added keys, removed keys, changed values) rather than just line-by-line text changes. For code files, the standard Diff Checker is ideal — it shows exactly which lines were added, removed, or modified, similar to what git diff produces.

Related Inspect Tools

GDV

Git Diff Viewer

Paste unified diff output from git diff and view it with syntax highlighting, line numbers, and side-by-side or inline display

ZIP

Compression Tester

Test and compare Brotli, Gzip, and Deflate compression ratios for text content — sizes, savings, and speed

TS6

TypeScript 6.0 Migration Checker

Analyze your tsconfig.json for TS 6.0 breaking changes, deprecated options, new defaults, and get a readiness grade with fixes

SEC

AI Code Security Scanner

Scan JavaScript and TypeScript code for vulnerabilities — hardcoded secrets, injection, XSS, SSRF, prototype pollution, and 20+ security checks