From JSON formatter to security audits: the best online tools, no signup
The best free online tools, grouped by area: development and data (JSON, YAML, CSV, regex, cron), files and images (conversion, metadata, QR), network and DNS (propagation, DoH, email), security and audit (certificates, JWT, CSP, passwords), calculators and games. No registration, no usage limits.
Development and data
22 tools
JSON formatter and validator
Format, validate, minify, sort keys and generate TypeScript interfaces from JSON. Fully.
Open toolJSON to TypeScript/Go/PHP
Generate TypeScript interface, Go struct and PHP class from JSON. Nested objects, optional/required inference. Multi-target.
Open toolYAML / JSON / TOML converter
Bidirectional YAML, JSON, TOML conversion with strict validation.
Open toolCSV / TSV / JSON converter
CSV or TSV to JSON and back, RFC 4180 compliant parser. Auto-detect delimiter, headers, encoding.
Open toolSQL formatter
Multi-dialect SQL formatter: MySQL, PostgreSQL, SQLite, MS SQL T-SQL, BigQuery, Snowflake, Oracle PL/SQL. Configurable indent, keyword case and minify mode.
Open toolMarkdown <-> HTML converter
Bidirectional Markdown -> HTML and HTML -> Markdown conversion. GitHub Flavored, table support, live preview.
Open toolcURL to Code Converter
Convert a cURL command into JavaScript fetch, PHP cURL, Python requests or Node. Headers, auth and body handled.
Open toolHTML / CSS / JSON / XML minifier
Minify and beautify for HTML, CSS, JSON and XML with inline compression stats. Preserves significant whitespace inside pre, textarea, script and style.
Open toolText and JSON diff online
Side-by-side text or JSON comparison with the Myers algorithm, unified patch export format.
Open toolRegex tester
Regex tester with match highlight, groups, flags (gimsuy). Pattern library categorized (email, URL, IP, phone, dates).
Open toolGlob pattern tester
Test glob patterns (*, **, ?, [abc], {a,b}) against file lists. Sh syntax + minimatch + gitignore.
Open toolCron expression parser
Parse 5-field POSIX cron + aliases (@yearly, @hourly) + weekly visualizer + next 20 runs. Natural language input.
Open toolUnix timestamp converter
Epoch <-> ISO 8601 with live multi-timezone and automatic DST. Batch CSV for timestamp lists.
Open toolText case converter
UPPERCASE, lowercase, camelCase, snake_case, kebab-case, PascalCase, Title Case with proper accent handling.
Open toolMulti-language slug generator
URL-friendly slugs from Italian, Spanish, French, German, English. Proper diacritic handling, batch CSV.
Open toolLorem ipsum generator
Classic Latin, Italian filler, Cicero original, geek/dev fillers, emoji. Multi-style.
Open toolMock data generator
Fake data generator (users, emails, addresses, companies) multi-locale (en/it/es/de/fr). Output JSON, CSV, SQL INSERT.
Open toolUUID, ULID, NanoID generator
UUID v4/v7, ULID timestamp-ordered, NanoID, bulk up to 10K, CSV/JSON export. Native crypto-safe.
Open toolHash calculator
MD5, SHA-1, SHA-256, SHA-384, SHA-512 from text or file.
Open toolEncoder / Decoder online
Base64, URL, HTML entities, Unicode, JWT decode, images to Data URI. Six tools in one.
Open toolJWT decoder
Decode JWT tokens with header and payload split, claim explainer, expiry countdown and optional HS256 signature verification via WebCrypto.
Open toolMojibake steganography
Light Unicode-safe steganography: each byte becomes a random higher codepoint.
Open toolFiles and images
8 tools
Image converter
Convert images between PNG, JPEG, WebP and AVIF and resize them in your browser, with quality and file-size control. No upload.
Open toolPhoto EXIF metadata
Extract and read the EXIF metadata of one or more photos (camera, shot, date, GPS) with a forensic SHA-256. Readable values. No upload.
Open toolPDF metadata
View a PDF's metadata (title, author, software, dates, pages, encryption) right in your browser. No upload, nothing sent to a server.
Open toolImage perceptual hash
Compute aHash, dHash and pHash of an image and compare two images with the Hamming distance. All in your browser, no upload.
Open toolQR code generator
QR codes for URLs, Wi-Fi networks, vCard contacts and SEPA wire transfers in EPC069-12 format with IBAN validation. PNG and SVG export, static payload with no intermediate redirect.
Open toolQR Code reader
Decode a QR Code from an image or screenshot in your browser. Recognises URL, Wi-Fi, vCard, SEPA and text. No upload, nothing sent.
Open toolColor picker and converter
HEX, RGB, HSL, OKLCH, Lab. WCAG AA/AAA contrast checker, palette generator.
Open toolOG image preview
Preview OpenGraph meta tags for Facebook, X/Twitter, LinkedIn, Discord. Validation of meta tags.
Open toolNetwork and DNS
5 tools
DNS propagation checker
Compares the zone's authoritative nameservers against 58 public resolvers, reads the remaining cache TTL of each one and tells you whether a mismatch is propagation in progress or ordinary GeoDNS.
Open toolDNS over HTTPS tester
Browser-side DoH queries via Cloudflare 1.1.1.1. Types A, AAAA, MX, TXT, NS, CNAME. No backend, fully.
Open toolEmail DNS validator (SPF, DKIM, DMARC)
Parser and validator for SPF, DKIM, DMARC records + MX lookup + multi-resolver compare (Cloudflare, Google, Quad9). For email deliverability audits.
Open toolHTTP status codes reference
Complete HTTP status code reference RFC 9110 (1xx-5xx) + curl example for each + when to use vs when not.
Open toolAdblock test (check your ad blocker)
A privacy-first test that measures, per layer, network/DNS blocking and cosmetic filtering across 50+ real ad networks and trackers. For uBlock Origin, Pi-hole, AdGuard, NextDNS, Brave.
Open toolSecurity and audit
9 tools
HTTP Security Headers Analyzer
Audit HTTP response headers for CSP, HSTS, X-Frame-Options, Permissions-Policy. NIS2 art. 24 + OWASP mapping. Severity-coded findings.
Open toolCSP Builder and Validator
Build an XSS-proof Content-Security-Policy or validate the one you already use, with a weakness report. Client-side.
Open toolSSL/x509 Certificate Decoder
Paste a PEM certificate and read Subject, SAN, issuer, validity and fingerprint. Everything in your browser, no data sent.
Open toolJWT security audit
Security audit of JWT tokens: alg=none detection, weak HS256 secret brute force, missing claims, oversized lifetime. OWASP-style findings with normative references.
Open toolBcrypt and Argon2 Password Hash
Generate and verify bcrypt and Argon2id hashes in your browser. Adjustable cost factor, no password sent over the network.
Open toolEncrypt text and files (AES-256)
Encrypt and decrypt text or files with AES-256-GCM and a password, all in your browser. Key via PBKDF2, random salt and IV. No upload.
Open toolSecure password generator
120 random passwords generated with the unbiased method, ASCII and alphanumeric, click to copy.
Open toolComposer audit
Parse composer.json/lock with statistics, EOL detection (Laravel/Symfony/PHPUnit), recommendations. Triage tool, no remote CVE lookup.
Open toolApache/Nginx config linter
Security lint for Apache.htaccess or Nginx server blocks. Auto-detects dialect. Findings on weak SSL, exposed status, missing headers.
Open toolCalculators and finance
1 tools
Games
1 tools
Why these tools
Every tool in this hub solves a concrete problem met in real consulting work. Development and data for everyday code work: formatting, converting between formats, trying a regular expression or a schedule before it reaches production. Files and images to open, convert and look inside a file without uploading it anywhere. Network and DNS to find out what a domain actually answers, where and when. Security and audit for certificates, headers, credentials and dependencies. Plus a few calculators and games, for the rest of the day. All free, all maintained.
Need a custom-built tool for your company?
If one of these tools inspired you, but your use case requires integration into your backend, custom logic, or end-to-end automation, let's talk. I do senior backend consulting on PHP, Laravel, Symfony, unmanaged Linux infrastructure, applied cybersecurity, AI/LLM integration in production.
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