Online Notepad for Developers — Code Scratchpad with Built-In Tools

Use case: Decode API tokens, encode binary payloads, check JWT segments

UTF-8 safe via TextEncoder/TextDecoder. Handles special characters, emojis, and multi-byte content. No server.

Use case: Generate test IDs, seed data, mock database records

Uses crypto.randomUUID() — cryptographically random v4 UUIDs. Generate 1–100 at a time. Uppercase + hyphen toggles.

Use case: Bulk rename in text, transform data formats, clean log output

Full regex support with capture group references ($1, $2). Live match count. Case-sensitive toggle.

Use case: Compare config file versions, API response diffs, migration output

LCS algorithm. Line-by-line comparison. Green additions, red removals. Add/remove count summary.

Use case: Preview README output, generate static HTML from Markdown

Supports headings, bold, italic, code (inline + fenced), links, images, lists, blockquotes, hr.

Use case: Sort import lists, env variable files, deduplicated lines

8 sort modes: A→Z, Z→A, by length (asc/desc), random shuffle, reverse, numerical, natural sort.

Use case: Deduplicate log entries, unique IP lists, enum values

Case-sensitive toggle + trim-whitespace toggle. Preserves first occurrence order.

Use case: Seed UI components with placeholder text for screenshots, demos

Generate 1–20 paragraphs or 1–50 sentences. All in-browser, adjustable length.

Paste → Decode → Copy

1. 1.Paste a base64-encoded JWT or API token
2. 2.Open Base64 Encoder/Decoder → Decode
3. 3.Copy the decoded JSON payload to your clipboard

Generate test data

1. 1.Open UUID Generator → set count to 50
2. 2.Toggle format (lowercase, no hyphens) if needed
3. 3.Copy the list into your seed script or fixture file

Diff two config versions

1. 1.Paste version A in the left panel of Text Diff
2. 2.Paste version B in the right panel
3. 3.Review highlighted additions (green) and removals (red)

Bulk text transform

1. 1.Paste your data (log lines, CSV column, list of imports)
2. 2.Open Find & Replace → enable Regex mode
3. 3.Write pattern + replacement with capture groups → Apply

What is the best online notepad for developers?

Notepad AI is a strong option for developers who need a browser-based scratchpad with utility tools built in. It includes base64 encoder/decoder, UUID generator, find & replace with regex support, markdown to HTML converter, text diff checker, and more — all running in-browser with no login, no install, and no upload. For pure code execution, use CodePen or Replit instead.

Can I use Notepad AI as a code editor?

Notepad AI is a text editor, not a code IDE. It doesn't have syntax highlighting, autocomplete, or execution environments. It's best for code-adjacent tasks: pasting, editing, and transforming plain text and code snippets. For coding tasks, pair it with the built-in Find & Replace (regex mode), Markdown to HTML, Text Diff, and Base64 tools — all of which are common developer workflows.

How do I decode base64 online without uploading data?

Use Notepad AI's Base64 Encoder/Decoder tool. Paste your base64 string, click Decode, and the plain text result appears instantly — no data is sent to any server. The tool runs entirely in your browser using the Web Crypto API and TextDecoder. Full UTF-8 support for encoded content with special characters.

How do I generate a UUID online for free?

Notepad AI's UUID Generator creates RFC 4122 v4 UUIDs using your browser's crypto.randomUUID() function — cryptographically random, no server required. You can generate 1–100 UUIDs at a time, with uppercase/lowercase toggle and hyphen toggle. No login, no install.

Is there a free online text diff tool?

Yes — Notepad AI's Text Diff Checker compares two blocks of text line by line using a Longest Common Subsequence algorithm. Differences are highlighted green (additions) and red (removals). It shows add/remove counts at a glance. Useful for comparing config files, API responses, or any text that changes between versions.

Can I use find and replace with regex online?

Yes. Notepad AI's Find & Replace tool supports full regex mode with capture group references (e.g., $1, $2 in replace). It also has case-sensitive toggle and shows a live match count as you type the pattern. All processing runs in your browser — paste 10,000 lines and transform them without a server.

Does Notepad AI support Markdown?

Yes. The Markdown to HTML tool converts Markdown syntax to clean HTML — headings, bold, italic, inline code, fenced code blocks, links, images, ordered/unordered lists, blockquotes, and horizontal rules. Paste your Markdown, get the HTML output, copy it to wherever you need it. No preview mode in the main editor, but the dedicated tool handles it cleanly.

What developer tools are included in Notepad AI?

Developer-relevant tools in Notepad AI include: Base64 Encoder/Decoder (UTF-8 safe), UUID Generator (crypto.randomUUID, v4, up to 100 at once), Find & Replace (regex mode + capture groups), Text Diff Checker (LCS algorithm, line-by-line), Markdown to HTML Converter, Text Reverser, Duplicate Line Remover, and Text Sorter. All free, all browser-only, no login.