JSON Formatter JSON FORMAT
Validate and beautify JSON with precise line-and-column error reporting; minify to a single line in one click.
v2.0 · 107 tools ready · runs locallyEverything beyond coding,
Everything beyond coding,
hand it to ⌘K
DevKit is a fully local developer toolkit — JSON, regex, hashes, JWT, image compression… Your data never leaves the browser. Open and use, works offline.
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codesmith@devkit — local
107
tools · all live
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data uploaded
<40ms
local response
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free · no login
Timestamp Converter TIMESTAMP
Convert timestamps to dates and back; auto-detects 10-digit seconds and 13-digit milliseconds, with time zones and relative time.
Base64 Encode / Decode BASE64
UTF-8-safe Base64 encoding and decoding — no garbled CJK text; independent encode and decode panels that never interfere.
Hash Calculator HASH DIGEST
Real-time SHA-1 / 256 / 384 / 512 digests computed locally with WebCrypto — perfect for verifying file fingerprints.
Password Generator PASSWORD
Generate strong passwords locally: pick length and character sets, exclude look-alikes; live entropy-based strength meter.
Image Compressor IMAGE COMPRESS
Drop in a photo and compress it locally — WebP first with automatic JPEG fallback, adjustable quality; phone photos shrink to shareable sizes.
Random String Generator RANDOM STRING
Generate random strings locally with configurable length, character set and look-alike exclusion — great for test data and throwaway tokens.
Text Extractor TEXT EXTRACT
Pull URLs, emails, IPs, phone numbers, hashes and dates out of any text in bulk — categorized, deduped and copied in one click; stop hand-picking from logs and traffic dumps.
Box Shadow Generator BOX SHADOW
Visually dial box-shadow — offset X/Y, blur, spread, color and inset, with multiple layers, live preview and one-click CSS copy.
Image Cropper IMAGE CROP
Drag a crop region on a canvas with 1:1 / 4:3 / 16:9 presets and export PNG or JPEG locally — the image is never uploaded and the source stays intact.
curl to Code CURL TO CODE
Paste a curl command and get fetch / axios / Python requests / Go snippets — headers, data and url-encoding flags parsed automatically.
Token Counter & Cost Estimator TOKEN COUNTER
Estimate LLM token usage and API cost locally — pick a model to see token count, input/output cost and context-window usage; nothing is uploaded.
02
DATA & PROCESS
DATA & PROCESSJSON · Timestamps · Regex · Text stats
JSON Formatter JSON FORMAT
Validate and beautify JSON with precise line-and-column error reporting; minify to a single line in one click.
Timestamp Converter TIMESTAMP
Convert timestamps to dates and back; auto-detects 10-digit seconds and 13-digit milliseconds, with time zones and relative time.
Regex Tester REGEX TESTER
Real-time matching with per-group highlighting and capture-group breakdown; empty matches are skipped automatically so complex patterns are safe to test.
Text Stats TEXT STATS
Live character, word, line and UTF-8 byte counts; mixed CJK/English text is counted per han character and per whole word.
Case Converter CASE CONVERT
One-click conversion between UPPER, lower, Title, camelCase, snake_case and kebab-case — stop retyping field names.
Full/Half Width Converter FULL/HALF WIDTH
Two-way full-width ↔ half-width conversion with automatic ASCII offset; great for cleaning "wide" characters copied from Word or chat apps.
Thousand Separator THOUSAND SEP
Add or remove thousands separators for long numbers, negatives and decimals included — amounts and big numbers read at a glance.
Text Diff TEXT DIFF
Two-pane text comparison in line or character mode with green-add / red-remove highlighting — spot every change instantly.
CSV ⇄ JSON Converter CSV ⇄ JSON
Two-way CSV ↔ JSON conversion that handles commas and newlines inside quoted fields, with delimiter and header options.
Cron Parser CRON PARSER
Parse 5/6-field cron expressions into plain-language descriptions and upcoming run times, with range validation.
JSON Tree Viewer JSON TREE
Render JSON as a collapsible hierarchy tree — deep nesting becomes readable at a glance, with precise error locating.
JSON ⇄ YAML / XML JSON ⇄ YAML / XML
Four-way conversion between JSON, YAML and XML (with attribute and text-node conventions) — API debugging and config migration in one place.
Line Tools LINE OPS
Batch line operations: trim whitespace, delete empty lines, order-preserving dedupe and sorting, freely combined — a cleanup tool for lists and logs.
HTTP Status Codes HTTP STATUS
A quick reference of 60 common HTTP status codes with meanings and category filters — stop digging through docs when debugging APIs.
JSONPath Query JSONPATH
Extract and filter JSON locally with JSONPath expressions — recursive descent, slices and conditional filters; matched values and paths side by side.
Math Expression Evaluator MATH EVAL
Evaluate math expressions safely — + - * / % ^, parentheses, functions (sin / sqrt / log…) and constants, with live results and readable errors.
Set Operations SET OPS
Treat lines of text as sets: intersection, union, difference, dedupe and duplicate detection at line level, with optional whitespace and case folding — compare two lists the easy way.
Text Extractor TEXT EXTRACT
Pull URLs, emails, IPs, phone numbers, hashes and dates out of any text in bulk — categorized, deduped and copied in one click; stop hand-picking from logs and traffic dumps.
JSON Schema Builder & Validator JSON SCHEMA
Infer a draft-07 schema from a JSON sample, then validate data against it — errors pinpointed to JSON Pointer paths, common keywords covered, fully local.
JSON Repair JSON REPAIR
One-click repair of broken JSON — single quotes, unquoted keys, trailing commas, // and /* */ comments, smart quotes and truncation become valid JSON, with precise locations when unfixable.
JSON ⇄ JSONL Converter JSON ⇄ JSONL
Convert between JSON arrays and NDJSON (one JSON per line) in both directions, validating line by line and flagging bad line numbers; handles large text with a 10MB batching hint.
JSON Diff JSON DIFF
Semantic diff of two JSON documents — ignores key order and whitespace, with a tree view flagging added / removed / changed nodes; optionally ignore array order or string case.
03
ENCODE & SECURITY
ENCODE & SECURITYBase64 · URL · Hashes · JWT
Base64 Encode / Decode BASE64
UTF-8-safe Base64 encoding and decoding — no garbled CJK text; independent encode and decode panels that never interfere.
URL Encoder / Decoder URL ENCODE
Two-way encodeURIComponent / decodeURIComponent with full URL breakdown into protocol, host, path and query params.
Hash Calculator HASH DIGEST
Real-time SHA-1 / 256 / 384 / 512 digests computed locally with WebCrypto — perfect for verifying file fingerprints.
JWT Decoder JWT DECODER
Split a three-part token into header algorithm, payload claims and expiry at a glance. Decode only — no signature verification.
Base Converter BASE CONVERTER
Convert between any base (2–36), integers and fractions alike — handy for memory addresses, color values and protocol fields.
HTML Entity Encoder / Decoder HTML ENTITIES
Escape < > & " ' to entities or restore <div> and A back to text — a staple for debugging front-end templates.
MD5 & HMAC MD5 & HMAC
Compute MD5 and HMAC-MD5 digests fully offline, with CJK text and arbitrary keys — handy for file fingerprints and legacy API signatures.
QR Code Reader QR SCANNER
Decode QR codes from an image locally — large images are auto-scaled for recognition; nothing is ever uploaded.
File Hash Checker FILE HASH
Drop a file to compute MD5 and SHA-1/256/384/512 digests locally — zero bytes uploaded; instantly tell if a download is intact.
Unicode Escape Converter UNICODE ESCAPE
Convert CJK text and Emoji to \uXXXX escapes or restore them, auto-merging surrogate pairs — turn mojibake in API logs readable in a second.
URL Parameter Editor URL PARAMS
Parse every part of a URL and edit query params in a table — change values, delete or add params and rebuild the link live, with auto-encoding.
JSON Escape / Unescape JSON ESCAPE
Escape text containing quotes, newlines and backslashes into a form safe to embed in JSON, or restore it — handy when writing fixtures and string literals.
HMAC Signature Generator HMAC SIGN
Compute HMAC signatures with SHA-1/256/384/512 — key and message in, WebCrypto computes locally, hex or base64 out.
AES Encryption AES CRYPT
AES-GCM encryption and decryption via WebCrypto with key and IV input, supporting base64 or hex for both text and ciphertext — sensitive data never leaves the browser.
htpasswd Generator HTPASSWD
Generate Apache htpasswd entries in bcrypt, apr1 (MD5) or SHA-1 format, hashing passwords locally — handy for Nginx and Basic Auth setups.
X.509 Certificate Parser X.509 CERT
Paste a PEM certificate to read subject, issuer, validity, serial number and public-key algorithm, with days-left and expiry status — ideal for debugging HTTPS and certificate chains.
HTML Entity Reference & Escape HTML ENTITIES
A reference of 120+ named entities (filterable live, click to copy) plus batch escape/unescape of whole text blocks, with optional named-entity output for non-ASCII.
Bcrypt Hash BCRYPT
Generate and verify Bcrypt password hashes ($2b$…) locally with a 4–15 cost factor; hashing and verification both run on-device, passwords never uploaded.
RSA Key Pair Generator RSA KEYS
Generate RSA key pairs locally in your browser (2048/3072/4096), exporting both PEM (SPKI public / PKCS8 private) and JWK; keys never leave the device and touch no server.
TOTP Authenticator TOTP
Local TOTP codes per RFC 6238 (HMAC-SHA1, refreshed every 30s) with multiple accounts and QR import; keys are stored only on this device — avoid shared computers.
04
GENERATORS
GENERATORSUUID · Strong passwords
UUID Generator UUID V4
Generate batches of cryptographically secure UUID v4; optional uppercase and hyphen stripping, one click for another batch.
Password Generator PASSWORD
Generate strong passwords locally: pick length and character sets, exclude look-alikes; live entropy-based strength meter.
Random String Generator RANDOM STRING
Generate random strings locally with configurable length, character set and look-alike exclusion — great for test data and throwaway tokens.
Lorem Ipsum Generator LOREM IPSUM
Generate standard Lorem Ipsum placeholder text with adjustable paragraphs and sentences per paragraph — fill prototypes in one click.
Mock Data Generator MOCK DATA
Batch-generate test data from field templates — names, phone numbers, emails, dates, enums; one template line yields N JSON records.
QR Code Generator QR CODE
Turn text or links into QR codes with adjustable error correction, size and colors; rendered locally, downloadable as PNG.
JSON to Type JSON TO TYPE
Infer JSON structure locally and generate type definitions for TypeScript, Go, Java and 9 languages total — int/float and nullable fields included.
NanoID Generator NANOID
Generate NanoIDs locally in batches: 21 chars by default, URL-safe alphabet (A-Za-z0-9_-) by default — shorter than UUID, ideal as IDs.
Placeholder Image Generator PLACEHOLDER
Type width, height, label and colors to render an inline SVG placeholder in real time — copy the SVG source or Data URI for prototypes and mockups.
UUID Parser UUID PARSE
Break a UUID into version, variant and embedded timestamps — v1 carries MAC and time, v7 stores a millisecond timestamp in its first 48 bits; decode it locally with ease.
Password Strength Analyzer PWD STRENGTH
Analyze your own password locally — estimate character space and entropy, flag common or repeated patterns and rough brute-force times; your input is never sent anywhere.
Code to Image CODE → IMAGE
Render syntax-highlighted code as a downloadable PNG — pick a theme and font size; ideal for share cards and docs, processed entirely locally.
05
DESIGN & MEDIA
DESIGN & MEDIAColor conversion · Image compression
Color Toolkit COLOR TOOLKIT
HEX / RGB / HSL conversion plus an auto-generated 10-step shade ramp (great for Tailwind palettes); one-click copy.
Image Compressor IMAGE COMPRESS
Drop in a photo and compress it locally — WebP first with automatic JPEG fallback, adjustable quality; phone photos shrink to shareable sizes.
Image Converter IMAGE CONVERT
Convert between WebP, JPEG and PNG locally; PNG→JPG gets a white background, with automatic fallback when WebP is unsupported.
Image to Base64 IMAGE BASE64
Two-way conversion between images and Base64 / Data URI — inline small icons or CSS backgrounds with one paste.
Color Converter COLOR CONVERT
Pure-math conversion across HEX / RGB / HSL / HSV / CMYK with input auto-detection — paste a color from your design file and go.
Color Palette Generator PALETTE
Derive harmonious palettes from a base color: complementary, analogous, triadic, split-complementary and monochrome — export CSS variables or Tailwind snippets.
Contrast Checker WCAG CONTRAST
WCAG 2.x contrast calculation with AA / AAA pass-fail, both directions at once — stop guessing at accessible color pairs.
CSS Gradient Generator GRADIENT
Dial in linear / radial gradients with 2–3 color stops, drag angle and position sliders and copy the CSS directly.
Box Shadow Generator BOX SHADOW
Visually dial box-shadow — offset X/Y, blur, spread, color and inset, with multiple layers, live preview and one-click CSS copy.
Border Radius Generator BORDER RADIUS
Visually tune border-radius with per-corner control in px or percentage — nail corners for cards, avatars and pill buttons in one place.
Cubic Bezier Generator CUBIC BEZIER
Drag the control points to shape a cubic-bezier easing curve, preview the motion live with an animated box, and copy the CSS timing-function or JS values.
Color Name & Mixer COLOR NAME
Map HEX / RGB values to and from common color names, and blend two colors by ratio into a new value — naming and mixing in one tool.
Image Cropper IMAGE CROP
Drag a crop region on a canvas with 1:1 / 4:3 / 16:9 presets and export PNG or JPEG locally — the image is never uploaded and the source stays intact.
Favicon Generator FAVICON GEN
Upload an image or type text / emoji to generate 16 / 32 / 48 / 180 / 512 favicons in one zip; canvas scaling and client-side zip, zero upload.
06
CODE FORMAT
CODE FORMATSQL · XML · YAML · TOML · Markdown
SQL Formatter SQL FORMAT
Beautify one-line SQL with uppercase keywords and indented clauses — a lifesaver when reviewing spaghetti queries.
XML Formatter XML FORMAT
Beautify or minify XML with tag-pair validation and error locating; declarations, comments and CDATA all handled.
YAML Formatter YAML FORMAT
Validate and beautify YAML, convert to and from JSON without escaping CJK — verify K8s / CI configs as you edit.
TOML Formatter TOML FORMAT
Validate and beautify TOML, convert to and from JSON — a helper for Cargo, pyproject and other Rust/Python configs.
Markdown Preview MARKDOWN PREVIEW
Live Markdown preview with tables, code blocks and blockquotes; raw HTML is always escaped — paste safely.
JavaScript Minifier JS MINIFY
Conservative JS minification: strips comments, indentation and blank lines while preserving strings and regexes verbatim — no renaming, still runs.
CSS Formatter CSS FORMAT
Two-way CSS beautify and minify: one declaration per line, tidy nesting; minify keeps /*! comments and collapses zero units without reordering selectors.
HTML Formatter HTML FORMAT
Beautify or minify HTML: block elements on new lines, inline elements untouched; script/pre content preserved verbatim so rendering never changes.
PX ⇄ REM Converter PX REM CONVERT
Batch-convert between px and rem with an adjustable root font size — paste in design specs for responsive styles.
JSON Minifier JSON MINIFY
Collapse formatted JSON into a single line in one click — strip newlines and indentation for smaller payloads and easier pasting into logs or URLs; precise error locating.
Tab / Spaces Converter TAB ⇄ SPACES
Convert between tabs and spaces in both directions with 2/4/8 width options — fix messy indentation from copied code in one click.
Line Ending Converter LINE ENDING
Normalize line endings to CRLF / LF / CR with automatic detection and per-style counts — a lifesaver for cross-platform script errors.
TypeScript Type Stripper TS TO JS
Strip type annotations, interfaces and generics from TypeScript source to get runnable JavaScript — a conservative, lexer-based pass that leaves anything ambiguous untouched.
HTML & SVG to JSX HTML TO JSX
Convert HTML / SVG snippets into React JSX — class→className, style strings to objects, self-closing tags and entities handled; perfect for pasting designer SVGs.
HTML to Markdown HTML → MD
Convert HTML to Markdown — keeps code blocks, tables, links, headings, lists, bold/italic and images; pure front-end DOMParser parsing with no heavy dependency.
07
UNIT CONVERT
UNIT CONVERTLength · Weight · Temperature · Volume · Area · Time · Data · Speed
Unit Converter UNIT CONVERT
Real-time conversion across length, weight, temperature, volume, area, time, data and speed — temperature offset handled correctly.
Date & Time Zone Difference DATE & TZ DIFF
See the gap between two dates in days, years and months at a glance (leap years and DST handled), plus wall-clock conversion across time zones.
Bandwidth & Data Rate Converter BANDWIDTH
Convert bit rates to byte rates (decimal 1000-based, with a strong Mb-vs-MB ×8 reminder) and estimate transfer time from file size and bandwidth.
Angle Converter ANGLE
Convert between degrees, radians, gradians and turns in real time — handy for CSS rotate and canvas math.
Chinese Numeral Converter CN NUMERAL
Convert numbers to Chinese uppercase/lowercase amounts with yuan/jiao/fen, negatives and decimals — zero merging and 整 suffix per accounting rules, ready for invoices.
08
REFERENCE
REFERENCEMIME types · Emoji search
MIME Type Lookup MIME LOOKUP
A quick extension ↔ MIME type lookup with live filtering by extension or media type — check Content-Type or upload validators in seconds.
Emoji Search EMOJI SEARCH
Search a built-in emoji library by keyword or category in real time; click any emoji to copy it — perfect for posts and README badges.
HTTP Headers Reference HTTP HEADERS
A reference of 60+ common request and response headers with usage, examples and security notes — filterable live by name, direction and category.
Time Zone Reference TIME ZONES
Browse IANA time zones with live current time and UTC offsets, searchable by name — handy for cron, log triage and cross-region meetings.
Git Command Cheat Sheet GIT CHEAT SHEET
Scenario-based Git command cheat sheet — undo, revert, branching, rebase, stash, submodules — searchable and copy-ready.
09
FILE TOOLS
FILE TOOLSFile info · On-device read
File Metadata Reader FILE META
Drop or pick a local file to read metadata — name, size, type, last modified and more; read entirely on-device, nothing is uploaded.
File Encoding Detector ENCODING
Drop a text or file to detect its encoding locally — UTF-8 / UTF-16 / GBK with BOM awareness — and preview the content decoded with the detected encoding.
File ⇄ Base64 FILE BASE64
Convert any file to Base64 or a Data URI, and restore pasted Base64 back to a downloadable file — 20MB cap, fully local.
File Type Identifier FILE SIGNATURE
Sniff a file's real type from its magic bytes (20+ signatures) and flag mismatches with its extension — catch files renamed to disguise themselves.
10
DEV TOOLS
DEV TOOLSURL slug generator
URL Slug Generator SLUGIFY
Turn titles or filenames into URL-friendly slugs: lowercase, spaces to dashes and special characters stripped — ready for routes and anchors.
curl to Code CURL TO CODE
Paste a curl command and get fetch / axios / Python requests / Go snippets — headers, data and url-encoding flags parsed automatically.
Token Counter & Cost Estimator TOKEN COUNTER
Estimate LLM token usage and API cost locally — pick a model to see token count, input/output cost and context-window usage; nothing is uploaded.
Dotenv ⇄ JSON Converter DOTENV JSON
Parse .env files to JSON — quotes, comments, export prefixes and inline # all handled — and convert JSON back to .env with live key validation.
chmod Calculator CHMOD CALC
Convert rwx notation to octal and back across owner/group/other, with setuid/setgid/sticky explained — directory and file scenarios included.
Semver Comparator SEMVER
Compare and sort semver versions with prerelease/build metadata, and test ranges like ^ ~ >= — stop guessing dependency upgrades.
IPv4 Subnet Calculator SUBNET CALC
Feed a CIDR to get network and broadcast addresses, usable host range and count, subnet mask, IP class and public/private scope; slice finer subnets by a new prefix.
OG & Meta Tag Generator OG META
Fill in title, description, URL and image to generate complete Open Graph + Twitter Card + standard meta code, with live WeChat / Telegram / X card previews and JSON-LD.
Docker Run to Compose DOCKER → COMPOSE
Turn a docker run command into an equivalent docker-compose.yml — ports, volumes, environment, name, restart policy and network, all parsed locally with zero upload.
Basic Auth Header BASIC AUTH
Encode user:password into an Authorization: Basic <base64> header with a copy-ready header and curl snippet; cross-linked with the HTTP Headers tool.
07
Scenes
ScenesPick a workflow, jump straight to the tools you need.
AI Data Prep
Clean data before feeding the model: validate, extract, query paths and re-encode in one flow.
Security Audit
Password hashing, keys, JWT, HMAC and Basic Auth — computed locally and discarded, zero upload.
Frontend Kit
Formatting, unit conversion, palettes, shadows and radii — preview and export right after writing styles.
DevOps Kit
Docker orchestration, permission bits, crontab, subnets and curl-to-code — deploy and debug on the go.
Format Convert
YAML/XML/TOML/SQL/Markdown/TS interconversion — paste and get the result instantly.
Text Cleanup
Case, full/half-width, dedupe, extract and set ops for batch processing of logs and copy.
06
Privacy promise
Zero upload
Every computation happens in your browser — tools never make a single network request.
Zero tracking
No accounts, no analytics scripts; localStorage only stores your theme and favorites.
Free forever
No paywalls, no usage limits. The whole site is a static page you can save locally.
Works offline
Save the page and it remains a complete toolbox even without a network.