How to Diff Two Copied Code Snippets

The quickest way to diff two copied snippets on Windows is VS Code's built-in clipboard compare. Paste the first snippet into a new file (Ctrl+N, then Ctrl+V), copy the second snippet, and press Ctrl+K then C to run File: Compare Active File with Clipboard. VS Code opens a side-by-side diff with every changed line highlighted. JetBrains IDEs have the same feature, and WinMerge or git diff --no-index work without an editor.

Compare with the clipboard in VS Code

1. Copy the first snippet (the original, or the version that works).
2. In VS Code, press Ctrl+N to open a new untitled file and Ctrl+V to paste it.
3. Copy the second snippet from wherever it lives: a browser, chat, a log or another file.
4. Back in the untitled file, press Ctrl+K, release, then press C. You can also open the Command Palette (Ctrl+Shift+P) and run File: Compare Active File with Clipboard.

The diff compares the whole active file with the clipboard, so keep only the first snippet in that file. Set the language mode (Ctrl+K M) if you want syntax highlighting.

If you've already copied both snippets, you don't need to find them again. Run File: Compare New Untitled Text Files (below), click into one side and press Win+V to paste the older copy from clipboard history, then do the same on the other side with the newer copy. How to use Windows clipboard history day to day covers turning history on.

Other ways to open a diff in VS Code

• Two empty sides: run File: Compare New Untitled Text Files from the Command Palette, then paste one snippet on each side.
• Two files in your workspace: select both in the Explorer, right-click and choose Compare Selected.
• From a terminal: code --diff a.txt b.txt opens the diff editor for two files.

Compare with the clipboard in JetBrains IDEs

IntelliJ IDEA, PyCharm, WebStorm and the other JetBrains IDEs have the same idea built in:

• Compare with Clipboard: right-click anywhere in the editor and choose Compare with Clipboard.
• Two pasted snippets: press Ctrl+Shift+A, search for Open Blank Diff Window, and paste one snippet into each panel.
• A scratch file: File > New > Scratch File (Ctrl+Alt+Shift+Insert) gives you a throwaway file with highlighting for the first snippet, without adding it to the project.

Diff from the command line

Save each snippet to a file, then use git diff. In PowerShell, copy the first snippet and run the first line, then copy the second and run the second:

Get-Clipboard -Raw | Set-Content -Path a.txt -Encoding utf8
Get-Clipboard -Raw | Set-Content -Path b.txt -Encoding utf8
git diff --no-index a.txt b.txt

--no-index lets git diff compare any two files, inside a repository or not. The output is a unified diff: lines starting with - come from a.txt, lines starting with + from b.txt. Useful options:

• --word-diff marks changed words inside a line, which helps when a long line differs by one argument.
• -w (--ignore-all-space) hides whitespace-only changes, such as re-indented code.
• --ignore-cr-at-eol hides differences that are only Windows versus Unix line endings.

Without Git, Command Prompt's fc /n a.txt b.txt lists differing lines with line numbers. In PowerShell, type fc.exe, because fc on its own is PowerShell's alias for Format-Custom.

Visual diff tools

Diffing JSON, SQL and other structured text

Two snippets can mean the same thing and still differ on every line. Normalise them before you compare:

• JSON: key order and formatting often differ between tools. Run both through jq -S . (sort keys and indent) and diff the results: jq -S . a.json > a.sorted.json. How to share large JSON payloads has more on saving JSON to files.
• Code from different editors: format both with the same formatter (in VS Code, Shift+Alt+F) so indentation and quote style match.
• Logs: strip timestamps and request IDs first, or every line will show as changed. How to copy error logs without grabbing half the console covers trimming a log before you copy it.

Is an online diff checker safe?

For public code, yes. For anything proprietary, or anything that might contain a token, password or customer data, use a local tool: whatever you paste into a web page is handled by someone else's site. Is it safe to paste tokens into online debuggers? explains what to check.

FAQ

What is the VS Code shortcut to compare with the clipboard?

Ctrl+K followed by C runs File: Compare Active File with Clipboard. To change it, open Keyboard Shortcuts (Ctrl+K Ctrl+S) and search for "Compare Active File with Clipboard".

Can you compare two selections in the same file?

Not directly. Copy one selection into a new untitled file, copy the other, and use Compare Active File with Clipboard.

Why does every line show as changed?

Usually line endings or indentation. Use git diff --no-index --ignore-cr-at-eol -w, or reformat both snippets the same way before comparing.

Related reading

• How to Copy an Error Log Without the Noise
• Is It Safe to Paste Tokens Into Online Regex and JWT Debuggers?
• How to Share Large JSON Payloads Without Pasting Them
• How to Use Clipboard History in Windows 11 (Win+V Tips)

Sources

• fileActions.ts (VS Code source, GitHub) — Compare Active File with Clipboard (Ctrl+K C) and Compare New Untitled Text Files.
• Command Line Interface (VS Code docs) — code --diff.
• Languages overview (VS Code docs) — Change Language Mode, Ctrl+K M.
• Compare files, folders and text sources (IntelliJ IDEA Help) — Compare with Clipboard and Open Blank Diff Window.
• Scratch files (IntelliJ IDEA Help) — Ctrl+Alt+Shift+Insert.
• git diff (Git documentation) — --no-index, --word-diff, --ignore-all-space and --ignore-cr-at-eol.
• fc (Microsoft Learn) — comparing two files, /n for line numbers.
• Get-Clipboard (Microsoft Learn) — the -Raw parameter.
• WinMerge — open-source differencing and merging tool for Windows.
• Meld — Windows installer and macOS binaries.
• Beyond Compare (Scooter Software) — runs on Windows, macOS and Linux; free trial.
• jq manual (jqlang) — --sort-keys.

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