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About Dev Tools

This started out of a simple frustration — there was no single place to do all the small things developers need day-to-day. JSON diffing here, Base64 decoding there, a cron builder somewhere else. Tabs everywhere. So we built our own toolkit, quietly, for personal use. When friends and colleagues got a look at it, they wanted in too. The feedback was warm and honest, and what started as a handful of tools grew steadily into what you see here.

Well-wishers kept nudging us to open it up — so we did. Dev Tools is free, carries no ads, and we never store or inspect your data — with one exception: when you use the share feature, a snapshot is saved server-side to generate a link, and anyone with that link can view it. It exists because developers deserve a calm, reliable place to get things done without distractions or paywalls. We hope it earns a permanent tab in your browser. See Privacy →

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Privacy & Data

Your data is never stored or seen by us. Everything you paste, upload, or test in these tools runs in your browser or is processed in-flight on the server — nothing is saved to a database, logged, or inspected. Close the tab and it's gone.

Share links are intentionally public. When you use the share feature, a snapshot of your data is saved server-side to generate a link. Anyone who receives that link can view the full content and share it further. Only share data you are comfortable making accessible to others. Shared links are automatically removed after 365 days of inactivity.

These tools are built for developer convenience. We want you to work fast and safely — that means your data belongs to you, not us.

Dev Tools — Free Online Developer Tools

A free, ad-free collection of browser-based utilities for developers. Validate JSON, compare diffs, encode Base64, generate UUIDs, test regex, decode JWTs, and more — all in your browser, nothing stored.

JSON Tools
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JSON Lint
Real-time validation, formatting, syntax highlighting, collapsible tree, XML/YAML conversion.
ValidateFormatXML/YAMLCollapseSearch
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JSON Diff
Side-by-side comparison of two JSON payloads. Missing, changed, added key detection with shareable links.
Before/AfterKey diffShareSync
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Schema Gen
Paste sample JSON → generate a Draft-07 JSON Schema with type inference, required fields, and format patterns.
Schema draftType inferPatterns
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Adv. Schema Builder
Visual JSON Schema editor with live preview, nested objects, $ref support, and Draft-07 keyword hints.
Visual$refDraft-07Preview
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Schema Validate
Validate JSON against a JSON Schema Draft-07. Live error reporting, path-level diagnostics, autocomplete.
ValidateErrorsAutocompleteDraft-07
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JSONPath Tester
Test JSONPath expressions live against JSON data. Supports $, .., [*], [?(@.key==val)] filters.
Live evalFilterRecursive
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Path Gen
Click any value in a JSON tree to instantly generate its JSONPath expression. Copy or export all paths.
Click-to-pathCopyExport
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Formats & Text
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Markdown Preview
Write Markdown and see rendered HTML side by side in real time. Copy rendered HTML with one click.
Live previewSplit viewCopy HTML
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CSV ↔ JSON
Convert CSV exports to JSON and back. Auto-detects delimiter, infers types, preview table, download.
CSV→JSONJSON→CSVPreviewDownload
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YAML Linter
Validate and format YAML. Convert YAML ↔ JSON. Syntax highlighting, error detection.
ValidateYAML↔JSONFormat
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SQL Formatter
Format SQL with keyword capitalisation and indentation. Syntax highlighting for SELECT, JOIN, WHERE and more.
FormatHighlightMinify
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Text Diff
Plain-text diff for any content — SQL, config files, log snippets, stack traces, YAML blocks.
Line diffWord diffStatsShare
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Auth & Encode
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JWT Decoder
Decode JWT / Bearer token header & payload, inspect claims, expiry countdown, flag expired tokens.
DecodeClaimsExpiryInspect
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Base64
Encode and decode Base64. URL-safe variant, file input, auto-detect direction, byte counter.
EncodeDecodeURL-safeFile
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Hash Generator
Generate SHA-256 / SHA-512 / SHA-1 hashes from text or file. Compare two inputs side by side.
SHA-256SHA-512SHA-1CompareFile
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Aa
String Utilities
Case conversion, stats, escape/unescape, transforms (sort lines, unique, reverse, number).
CaseStatsEscapeTransform
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ENV Parser
Parse .env files. Table view with type detection, secret masking, duplicate flagging. Export as JSON or shell.
ParseMask secretsExport
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Web & Network
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URL Builder
Parse URLs into components. Edit scheme, host, path, query params. Rebuild and copy. Encode/decode values.
ParseQuery paramsEncode
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IP / CIDR Tools
IP address classification, CIDR subnet calculator, bitwise display, range checker.
SubnetRange checkBitwise
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HTTP Status
Searchable reference for all HTTP status codes with descriptions, use cases, and category color coding.
Search1xx–5xxReference
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HTTP Verbs
Reference for all HTTP methods — safety, idempotency, request/response body, use cases, and request examples.
GET/POSTSafe/IdemExamplesFilter
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Time Zone Converter
Convert a date and time across any number of time zones. Add multiple targets, use Now, copy results.
Multi-zoneNowOffset
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DNS Lookup & Dig
Look up A, AAAA, MX, NS, TXT, CNAME, SOA records for any domain. Table view or classic dig terminal format.
All record typesDig viewServer-side
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Host Ping
TCP-based host reachability and latency checker. 4 probes, min/avg/max — works even when ICMP is blocked.
TCP pingAny portLatency
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Proxy Checker
Test HTTP, HTTPS, SOCKS4, and SOCKS5 proxies — single or bulk list. Shows live/dead status and latency.
HTTP/SOCKSBulk listLatency
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Dev Utilities
UUID Tool
Generate v1/v4 UUIDs, bulk generation, validate any UUID, inspect structure and timestamp.
v1/v4BulkValidateBreakdown
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Timestamp
Convert Unix epoch ↔ human date. ISO, local, UTC, relative time. Add/subtract durations.
Epoch↔DateISO 8601RelativeMath
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Regex Tester
Live regex matching with highlights, match list, named groups, flags, and common pattern presets.
Live matchGroupsFlagsPresets
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Cron Builder
Build and parse cron expressions. Supports 5-field and Spring 6-field. Preview next run times.
BuilderParserSpringNext runs
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Color Converter
Hex · RGB · HSL · oklch conversion with live swatch, WCAG contrast ratio, and shade/tint palette.
Hex/RGB/HSLWCAGPalette
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Base Converter
Real-time conversion between Decimal, Hex, Binary, Octal, ASCII. Bit inspector for 8/16/32-bit integers.
Dec/Hex/BinOctalASCIIBits
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QR Code
Generate QR codes from any text or URL. Choose size and error correction level, download as PNG.
Text/URLPNG downloadCustom size
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Why Dev Tools?
Free & Ad-Free
Every tool is completely free with no ads, no paywalls, and no upsells. Use as much as you need.
Private by Design
All processing happens in your browser or in-flight on the server. Nothing is stored or logged.
Built for Developers
Tools for the tasks you reach for every day: JSON validation, Base64, UUIDs, hashing, regex testing, and more.
Always Available
No sign-up or install required. Open a tab, use the tool, and get back to building.
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Your data stays yours
Everything you paste or upload is processed on-the-fly and never stored, logged, or inspected by us — use these tools freely and with confidence. When you use the share feature, a link is created so others can view that snapshot; anyone with the link can see and re-share it, so only share what you're comfortable making accessible. Learn more →