AppSvc online developer toolbox

Kr3 DevTools

Fast local utilities for encoding, JSON, hashes, timestamps, UUIDs, QR codes, text processing, and more.

All developer tools

Data

Format, convert, validate, and generate structured data for development workflows.

Batch Image CropBatch crop photos to a target size with cover crop or centered padding.
Batch JSON FormatterFormat or minify multiple JSON documents locally.
Code to ImagePaste code, tune the frame, and export a crisp PNG or SVG image.
Color ExtractionExtract a simple dominant palette from an image locally.
CSS Formatter / CompressorFormat or compress CSS locally.
CSV Table to SQLConvert a CSV table into SQL INSERT statements locally.
HTML FormatterFormat HTML markup locally.
HTML Symbols ReferenceReference common HTML entities locally.
HTML Table to Markdown TableConvert HTML tables into Markdown tables locally.
HTML to JSXConvert common HTML attributes into JSX syntax locally.
HTML to SQLConvert an HTML table into SQL INSERT statements locally.
Image CompressorCompress images locally with Squoosh-style quality and resize controls.
Image CropCrop local images with free selection or common photo presets.
Image Format ConverterConvert up to 100 images to PNG, JPEG, or WebP in your browser.
Image to IconConvert an image into icon-sized PNG and ICO files locally.
JavaScript Formatter / CompressorFormat or compress JavaScript locally.
JSON DiffFormat two JSON documents and compare them in a side-by-side highlighted diff.
JSON FormatterFormat, validate, and inspect JSON input as a readable tree in the browser.
JSON MinifierMinify and validate JSON input in the browser.
JSON to Crystal ClassInfer a Crystal JSON::Serializable class from JSON locally.
JSON to CSVConvert JSON into CSV locally.
JSON to HTMLConvert JSON into an HTML table locally.
JSON to IO-TSInfer an io-ts codec from JSON locally.
JSON to Pike ClassInfer a Pike class from JSON locally.
JSON to SarcasticConvert JSON into sarcastic TypeScript-like output.
JSON to SQLGenerate SQL INSERT statements from JSON locally.
JSON to SQL SchemaInfer a SQL table schema from JSON locally.
JSON to Swift StructInfer a Swift Codable struct from JSON locally.
JSON to TSVConvert JSON into TSV locally.
JSON to TypeScript InterfaceInfer a TypeScript interface from JSON locally.
JSON to YAMLConvert JSON into YAML locally.
Less to CSSCompile a small local subset of Less into CSS.
Markdown Table to HTML TableConvert Markdown tables into HTML tables locally.
SQL CompressorMinify SQL statements locally.
SQL FormatterFormat SQL statements locally.
SQL Schema to C# ClassGenerate a C# class from SQL schema locally.
SQL Schema to Python ClassGenerate a Python dataclass from SQL schema locally.
SQL Schema to TypeScript InterfaceGenerate a TypeScript interface from SQL schema locally.
SQL UnescapeUnescape SQL string literals locally.
YAML Formatter / CompressorFormat or compact YAML locally.
YAML to JSONConvert YAML into formatted JSON locally.

Encoding

Encode, decode, escape, and inspect common text and binary-safe formats.

Base64 CodecEncode and decode Base64 strings with UTF-8 support.
Base64 File DecodeDecode Base64 into a downloadable file locally.
Base64 File EncodeEncode a local file to Base64 without uploading it.
Base64 to HexConvert Base64 text into hexadecimal bytes locally.
CIDR CalculatorCalculate CIDR network details locally.
IP Info LookupLook up IPv4 or IPv6 details including ASN and country.
JSON Escape / UnEscapeEscape and unescape JSON string content locally.
JWT DecoderDecode, inspect, and verify JWTs locally.
Morse DecodeDecode Morse code into text locally.
Morse EncodeEncode text into Morse code locally.
Port Cheat SheetReference common network ports locally.
String EscapeEscape and unescape string literals locally.
URL CodecEncode and decode URL components or full URI strings.
URL ParseParse URL parts and query parameters locally.
UTF Encoding InspectorInspect UTF-8 and UTF-16 hex encodings locally.
UTF16 DecodeDecode UTF-16LE hex bytes locally.
UTF7 EncodeEncode and decode UTF-7 or IMAP UTF-7 locally.
UTF8 DecodeDecode UTF-8 hex bytes locally.
WebSocket TesterConnect to a WebSocket endpoint locally from the browser.

Crypto

Generate hashes, keys, signatures, and other browser-side cryptographic helper output.

3DES · DecryptPaste ciphertext and the matching key to recover Triple DES plaintext.
3DES · EncryptEnter plaintext and configure your key to create Triple DES ciphertext.
AES · DecryptPaste ciphertext and the matching key to recover AES plaintext.
AES · EncryptEnter plaintext and configure your key to create AES ciphertext.
bcrypt · Password checkEnter a password and bcrypt hash, then run a check to see whether they match.
CRC1 · DigestCalculate text digests individually or by line, choose an encoding, and compare results.
CRC16-CCITT-FALSE · Checksum calculatorCalculate text digests individually or by line, choose an encoding, and compare results.
CRC24 · DigestCalculate text digests individually or by line, choose an encoding, and compare results.
CRC32 · DigestCalculate text digests individually or by line, choose an encoding, and compare results.
DES · DecryptPaste ciphertext and the matching key to recover DES plaintext.
DES · EncryptEnter plaintext and configure your key to create DES ciphertext.
Hash generator · HMAC / PBKDF2Choose a hash, HMAC, or PBKDF2 to calculate digests, compare results, or derive keys.
htpasswd · GeneratorEnter a username and password, choose the bcrypt cost, and generate a password file entry.
JWT · Generator & signingEdit the header and payload, configure your key and time claims, and create a signed JWT.
Keccak-224 · Hash calculatorCalculate text digests individually or by line, choose an encoding, and compare results.
PGP · DecryptPaste your PGP message and private key, unlock it if needed, and recover the original text.
PGP · EncryptPaste the recipient’s public key and your message to create an encrypted PGP message.
PGP · Key pair generatorChoose an algorithm, identity, and optional passphrase, then generate and save your PGP keys.
PGP · SignSign a message with your private key using cleartext or detached signatures.
PGP · Signature verificationPaste the signed message and public key to check whether the signature matches.
Rabbit · DecryptPaste ciphertext and the matching key to recover Rabbit plaintext.
Rabbit · EncryptEnter plaintext and configure your key to create Rabbit ciphertext.
RC4 · DecryptPaste ciphertext and the matching key to recover RC4 plaintext.
RC4 · EncryptEnter plaintext and configure your key to create RC4 ciphertext.
RSA · DecryptPaste ciphertext and the matching key to recover RSA plaintext.
RSA · EncryptEnter plaintext and configure your key to create RSA ciphertext.
RSA · Key pair generatorChoose a key size, generate a new pair, and save the public and private keys.
RSA · Private to public keyPaste a PEM private key to extract and save its matching public key.
SHA3-512 · Hash calculatorCalculate text digests individually or by line, choose an encoding, and compare results.
SM2 · DecryptPaste ciphertext and the matching key to recover SM2 plaintext.
SM2 · EncryptEnter plaintext and configure your key to create SM2 ciphertext.
SM4 · DecryptPaste ciphertext and the matching key to recover SM4 plaintext.
SM4 · EncryptEnter plaintext and configure your key to create SM4 ciphertext.

Time

Parse, convert, and inspect timestamps, dates, countdowns, and schedule expressions.

CountdownCount down to a target time locally.
CrontabDescribe five-field cron expressions locally.
Timestamp ConverterConvert timestamps or date strings into readable date values.

Text

Process plain text, QR content, image text, and document-friendly content formats.

Arabic to RomanConvert Arabic numerals into Roman numerals locally.
Barcode GeneratorGenerate a barcode image locally.
Barcode ScannerScan a barcode from an image or camera.
Chinese to PinyinConvert Chinese text to pinyin locally.
English PluralizeConvert English words between singular and plural, process batches, and create count phrases locally.
Mermaid EditorEdit and preview Mermaid diagrams locally.
QR Code for EmailGenerate a QR code for email content.
QR Code for Ethereum AddressGenerate a QR code for an Ethereum address.
QR Code for Phone NumberGenerate a QR code for a phone number.
QR Code for SMSGenerate a QR code for an SMS payload.
QR Code for TextGenerate a QR code from plain text.
QR Code for URLGenerate a QR code from a URL.
QR Code ScannerScan a QR code from an image or camera.
Simplified to Traditional ChineseConvert between simplified and traditional Chinese locally.
Text Case ConverterConvert text into camelCase, snake_case, kebab-case, title case, or constant case.
Text ProcessorClean, filter, deduplicate, sort, and change case for line-based text locally.

Generator

Generate identifiers, styles, configuration, and other everyday developer assets.

Chmod CalculatorConvert between chmod octal and symbolic modes locally.
Color PickerPick and convert colors locally.
CSS Grid GeneratorGenerate CSS Grid snippets locally.
FC PlayerPlay NES / Famicom ROMs in the browser with EmulatorJS.
GBA PlayerPlay Game Boy Advance ROMs in the browser with EmulatorJS.
Loan CalculatorCalculate loan payment and interest locally.
LotteryRandomly pick items from a list locally.
Regex TesterTest regular expressions locally.
UUID / ULID GeneratorGenerate UUID v4 and ULID values locally.
UUID GeneratorGenerate RFC 4122 version 4 UUID values locally.
UUID ParserParse UUID version and variant information locally.