Browser-local developer utilities
Coder Box
Format JSON, convert CSV to JSON, preview sanitized Markdown, encode Base64 or URLs, inspect JWT payloads, generate UUIDs and hashes, and clean text locally.
Runs in your browser where possible. No upload needed for browser-local tools.
Inputs are not stored by Useful Atlas. Refreshing the page clears the current workspace.
JSON formatter ready.
JSON formatter and validator
Format readable JSON, minify valid JSON, and find parsing errors.
Large integers outside JavaScript's safe integer range can lose precision when parsed. Keep a source copy when exact numeric strings matter.
CSV to JSON converter
Convert comma, semicolon, or tab-delimited data into JSON objects using the first row as field names.
Quoted delimiters, doubled quotes, and quoted line breaks are supported. Every value stays a JSON string so IDs, leading zeroes, and exact source text are preserved.
Markdown preview
Preview headings, lists, links, tables, quotes, and code without sending the source to a server.
Preview HTML is sanitized. Scripts, forms, embedded frames, images, event handlers, and unsafe link protocols are removed.
Base64 and URL encoder
Convert UTF-8 text to Base64 or safely encode URL components.
UUID and cryptographic hash generator
Create UUID v4 values and SHA hashes with the browser's Web Crypto API.
UUID v4 generator
SHA hash generator
JWT inspector and Unix time converter
Decode token header and payload data or convert Unix timestamps without sending values to a server.
JWT payload inspector
Inspection only: decoding a JWT does not verify its signature, issuer, audience, or trustworthiness. Do not treat decoded content as authenticated.
Unix timestamp converter
Enter Unix seconds or milliseconds. The converter detects the unit from the value size and shows both UTC and local browser time.
Text cleaner and case converter
Measure text, clean whitespace, change case, or create a URL-friendly slug.
- Words
- 0
- Characters
- 0
- Characters without spaces
- 0
- Lines
- 0
One local workspace for everyday developer tasks
Coder Box keeps common transformations together so you can inspect an API response, prepare an encoded value, create identifiers, and clean copy without moving between unrelated sites.
Each action runs in client-side JavaScript. The page does not need an account, file upload, or tool-specific network request.
Good uses
- JSON: inspect payloads, validate configuration, and reduce whitespace.
- CSV: convert quoted comma, semicolon, or tab-delimited rows into JSON objects.
- Markdown: preview common Markdown with unsafe HTML removed.
- Base64 and URL: prepare API values and decode unfamiliar strings.
- UUID and hash: create identifiers and reproducible SHA digests.
- JWT and time: inspect token data and convert Unix seconds or milliseconds.
- Text: count, clean, re-case, and slugify working copy.
Related tools
FAQ
Does Coder Box upload my input?
No upload needed for browser-local tools. Inputs are not stored by Useful Atlas.
Which hash algorithms are available?
Coder Box supports SHA-256, SHA-384, and SHA-512 through the browser Web Crypto API.
Is Base64 encryption?
No. Base64 is a reversible encoding format. Do not use it to protect secrets or sensitive data.
Can the JSON formatter change large numbers?
JSON is parsed by JavaScript. Integers outside the safe integer range can lose precision, so keep a source copy when exact large numeric values matter.
Does the JWT inspector verify signatures?
No. It only decodes the header and payload locally. Signature, issuer, audience, expiry, and trust must be verified by the application that accepts the token.
Does CSV to JSON preserve leading zeroes?
Yes. CSV values remain JSON strings so identifiers, leading zeroes, and exact source values are not silently converted into JavaScript numbers.
Can Markdown preview execute scripts?
The preview sanitizes generated HTML and removes scripts, forms, frames, images, event handlers, and unsafe link protocols before rendering it.