Encoders & Converters

15 free tools · runs in your browser

Base64, URL, hash, binary, JSON/YAML/CSV converters and number-base tools — all running instantly in your browser. Every tool listed here is free and needs no account.

Encode and decode data in your browser: Base64, URL, HTML entities, binary, hashes such as SHA and MD5, and number-base conversions from base 2 to 36. JSON, YAML, and CSV translate between formats with local validation. These tools handle everyday escaping and integrity checks privately, with no server round-trip.

Base64 Encoder / Decoder

UTF-8-safe Base64 encode and decode

URL Encoder / Decoder

Percent-encode or decode URLs and params

HTML Entity Encoder / Decoder

Escape or unescape HTML entities safely

Number Base Converter

Binary, octal, decimal, hex and any base 2–36

Binary to Text Converter

Decode 0s and 1s into readable text

Hex to Text Converter

Decode hexadecimal into readable text

Hash Generator

SHA-256, SHA-1, SHA-512, MD5 & CRC32 checksums

JWT Decoder

Inspect JWT header, payload and expiry

Unix Timestamp Converter

Epoch to date and back, in your timezone

Roman Numeral Converter

Numbers to Roman numerals and back

Number to Words Converter

Spell out numbers in English words

JSON Formatter & Validator

Beautify, validate and minify JSON

JSON to YAML Converter

Two-way JSON and YAML conversion

JSON to CSV Converter

Flatten JSON arrays into CSV spreadsheets

CSV to JSON Converter

Spreadsheet rows to clean JSON objects

Related guides

All guides

Encoders & Converters12 JSON Syntax Errors and Why Parsers Reject ThemJSON is strict on purpose: it is a wire format between systems that share no runtime, so every ambiguity has to be settled by whoever wrote the file. That turns an ordinary slip — a trailing comma, a single-quoted name, a comment — into a hard parser failure, and one slip, a repeated key, into silent corruption. All twelve are shown broken and then fixed below; to check a file of your own, the JSON Formatter linked from this guide parses it locally.6 min read · Read →Encoders & ConvertersWhat Is Base64 Encoding? The 33% Overhead ExplainedBase64 writes any byte as one of 64 safe ASCII characters, which makes binary survivable in text-only channels and costs about 33% more space. It is an encoding, not encryption, and nobody needs a key to undo it. What the alphabet and the padding rules actually specify is below; if you just need a string turned into Base64, the Base64 Encoder / Decoder tool linked from this guide runs in your browser.6 min read · Read →Encoders & ConvertersURL Encoding: %20, %2F, Plus Signs & RFC 3986Two escaping systems, one job each. Percent-encoding makes a value safe to travel inside a URL: %2F is an escaped slash, %3F an escaped question mark, %20 an escaped space. HTML entities solve a different problem entirely, making text safe inside markup rather than inside an address. Which one you need, what RFC 3986 actually requires, and the three mistakes that break most links are below; to convert a real string instead, the free URL Encoder / Decoder applies exactly those rules locally.7 min read · Read →

In this collection

Formats in, formats out

Encodings are where copy-paste debugging lives. The Base64 Encoder/Decoder handles full UTF-8 including emoji, the JWT Decoder exposes headers, payloads, and expiry without sending tokens anywhere, and the Hash Generator computes SHA-256, SHA-1, SHA-512, MD5, and CRC32 checksums for integrity checks. URL and HTML-entity codecs cover the everyday escaping chores that come up when moving data between systems, from query strings to legacy markup. Each tool accepts raw input and returns the transformed value immediately, so you can iterate without reloading the page. You can chain tools together, feeding one output into the next, without ever leaving this category.

For structured data, the JSON Formatter validates with exact error locations, JSON to YAML and JSON to CSV translate both directions, and the Number Base Converter spans bases 2 through 36 alongside dedicated binary, hex, timestamp, and Roman-numeral converters. A typical session decodes a token, checks its hash, reformats the payload, and converts it into the shape the next system expects. Each tool shows the result immediately so you can iterate quickly, and error messages point at the exact character that caused the problem.

Key tools include Base64 Encoder/Decoder for binary-safe text, the JWT Decoder for inspecting tokens, the Hash Generator for integrity checks, the JSON Formatter for validating payloads, and the Number Base Converter for low-level formats. Each one covers a specific encoding need so you are not hunting through one general converter for everything, and each reports errors in plain language rather than opaque codes, which makes debugging faster when a payload does not decode the way you expected.

Paste payloads freely — validation runs entirely in your tab. Tokens, hashes, and JSON blobs are never uploaded, which matters when the payload contains API keys, session data, or customer information. Every transformation in this category stays local, so there is no server round-trip to log or intercept, and nothing you paste is stored anywhere but your own browser while you are on the page.

Common uses include verifying a JWT before deploying it, checking a file hash after download, converting configuration between JSON and YAML, and encoding data for URL-safe transport. To get started, paste the value you want to transform into the matching tool and read the result immediately. Every transformation runs in your tab, so a token or hash you check never leaves your machine. The related guides link back to two or three tools from this category for worked examples, so you can see a complete decode-verify-reformat flow before you begin.

All 15 of these run client-side in your browser: nothing you paste or drop here is uploaded, and no tool in this category contacts a third-party service. Results are copied or saved straight from the page. For worked examples, the related guides above each link back to 2–3 tools from this category.

All Encoders & Converters tools (15)