# Free online web tools
83 utilities I use daily: DNS, SSL, email security, minifiers, generators and validators. No sign-up, no limits, and nothing you paste leaves your browser except in the network tools.
Developer Tools
A collection of highly useful tools, mainly for developers — and not only for them.
.gitignore Generator
Build your .gitignore from 312 official templates, including Bun, Tauri, Expo, NestJS and Cursor. It explains what each rule ignores and tests whether a path is excluded.
Barcode Generator
Create EAN-13, EAN-8, UPC-A, Code 128, Code 39, ITF-14 and Codabar barcodes. It works out the check digit for you and downloads as SVG or PNG. All in your browser.
Base64 Encoder and Decoder
Encode and decode text in Base64 with UTF-8 support and a URL-safe variant. Also convert files and images to Base64 or a Data URL. No sign-up.
chmod Permissions Calculator
Convert Linux permissions between checkboxes, octal and ls notation, with special bits and a umask calculator. Gives you the chmod command ready to paste.
CSS Beautifier
Format and unminify CSS, SCSS and Less with Prettier. Choose indentation and line width, then download the result. All in your browser, nothing uploaded.
cURL to Code Converter
Convert a cURL command into ready-to-copy code in PHP (Laravel and Guzzle), JavaScript (fetch), Node.js (axios), Python (requests) and Go. All in your browser.
Docker Compose Validator
Validate your compose.yaml against the official Compose schema and catch key typos, wrong types and YAML errors, with the exact line. All in your browser.
HEX, RGB and HSL Color Converter
Convert colors between HEX, RGB and HSL instantly. Includes a picker, alpha channels, a tints-and-shades palette and a WCAG contrast check.
HTML Beautifier
Format and indent HTML and Vue templates with Prettier, including embedded CSS and JavaScript. Choose indentation and line width. All in your browser.
HTML Minifier
Minify your HTML by removing all unnecessary characters.
JavaScript Beautifier
Format and unminify JavaScript, TypeScript and JSX with Prettier. Control quotes, semicolons, indentation and line width. All in your browser.
JSON to TypeScript & Code Converter
Convert any JSON into TypeScript interfaces, Zod schemas, PHP classes, Python dataclasses or Go structs. Detects nested and optional types. All in your browser.
MD5 & SHA Hash Generator
Compute the MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text or file, with a checksum verifier. All in your browser, no sign-up.
Mexican ID Validator — RFC, CURP, CLABE, NSS
Check whether an RFC, CURP, CLABE or NSS is correct. Detects the type on its own, verifies the check digit and breaks down every part of the ID. All in your browser.
Password Strength Analyzer
Measure how long your password really holds, spot the Spanish patterns other meters miss, and check whether it has leaked without ever sending it. All in your browser.
QR Code Generator
Create QR codes for URLs, WhatsApp, WiFi, vCard contacts, email, phone or SMS, with your logo in the centre. PNG or SVG, no watermark or signup, and nothing leaves your browser.
Regex Tester
Test regular expressions in real time with match highlighting, capture groups, flags, $1 replacement and a quick reference. No sign-up.
Secure Password Generator
Random passwords or easy-to-remember passphrases (five random words, English or Spanish), in bulk and with a live entropy meter. Everything in your browser, nothing is sent.
Unix Timestamp Converter
Convert Unix timestamps to a readable date (ISO, UTC, local and relative time) and dates back to a timestamp, with seconds/milliseconds detection and a live clock. No sign-up.
URL Encoder and Decoder
Encode and decode URLs and parameters instantly, with a component or full-URL variant. Includes a query string parser. No sign-up.
UUID Generator
Generate random v4 and time-ordered v7 UUIDs in bulk, with format options and download. Includes an inspector that detects version and variant. No sign-up.
Word and Character Counter
Count words, characters, sentences and paragraphs in real time, with reading time and keyword density. Ideal for SEO, essays and social media.
CSS Minifier
Minify CSS in your browser with csso: strips whitespace and comments, shortens values and merges duplicate rules without changing the cascade. Keeps /*! licenses */ and calc(). Nothing uploaded.
JavaScript Minifier
Minify your JS by removing all unnecessary characters.
JSON Validator and Beautifier
Validate, beautify and format JSON online for free. Instantly spot syntax errors, indent or minify your JSON and copy it with one click.
SQL Formatter / Beautifier
Format and beautify your SQL code with ease.
HTML Entity Converter
Encode or decode HTML entities for any given input.
JWT Decoder and Verifier
Decode the header and payload of a JSON Web Token and verify its HS256/384/512 or RS256/384/512 signature.
AI & LLM
Tools for working with language models: count tokens, calculate costs and see how your text is split. Deterministic and in your browser, with no API calls.
LLM Token Counter & AI Cost Calculator
Count the tokens in your text or prompt and estimate the cost across GPT-5, Claude, Gemini, Kimi K3, Grok and DeepSeek. Exact OpenAI counting, per-call and monthly costs, with prompt caching.
Tokenizer Visualizer
Paste text and see exactly which tokens a language model splits it into, with their IDs. Check why Spanish costs more tokens than English.
Check Tools
A collection of great checker-style tools to help you validate and verify.
BIMI Checker
Check a domain's BIMI record, which shows your brand logo next to authenticated email in the inbox.
Blacklist Checker (DNSBL)
Check whether an IP or domain appears on email blocklists (DNSBL) that hurt the deliverability of your messages.
CAA Checker
Check a domain's CAA records to see which certificate authorities are allowed to issue its SSL certificates.
DKIM Checker
Look up a domain's DKIM public keys by selector. Provide your selectors or let common provider selectors be probed.
DMARC Checker
Look up and analyse a domain's DMARC record —policy (p=), reporting (rua), percentage and alignment— with actionable warnings.
DNS Lookup
Find A, AAAA, CNAME, MX, NS, TXT and SOA DNS records for a host.
DNS Propagation Checker
Check a domain's DNS propagation by querying several resolvers worldwide and comparing their answers.
DNSSEC Checker
Check whether a domain is protected by DNSSEC, inspecting DS/DNSKEY records and validation of the chain of trust (AD flag).
Domain Health Report
Audit a whole domain in one query: DNS, SPF, DKIM, DMARC, DNSSEC, CAA, TLS certificate and security headers, with a prioritised list of what to fix.
Email Auth Checker (SPF, DKIM, DMARC)
Audit a domain's SPF, DKIM and DMARC records and get a graded report with fixes to stop email spoofing.
Email Header Analyzer
Analyze an email's headers in your browser and review the Received route with delays plus the SPF, DKIM and DMARC verdicts.
HTTP Security Headers
Analyse a site's HTTP security headers (HSTS, CSP, X-Frame-Options and more) and get a grade plus the ones you are missing.
MTA-STS Checker
Check a domain's MTA-STS policy (DNS record and .well-known file) that enforces TLS for inbound email.
MX Lookup
Look up a domain's mail servers (MX records), their priority and the IPs they resolve to.
SPF and DMARC Record Generator
Build your domain's SPF and DMARC records with a wizard: pick your email providers and get the TXT ready to publish, with warnings about the mistakes that break mail.
SPF Checker
Analyse a domain's SPF record, detect its trailing qualifier (-all, ~all) and count DNS lookups against the limit of 10 (RFC 7208).
Subnet Calculator
Work out network, broadcast, host range, netmask and wildcard from CIDR notation, for IPv4 and IPv6. Split a block into subnets. All in your browser.
TLS-RPT Checker
Check a domain's TLS-RPT record to see whether it receives reports about email TLS encryption failures.
WHOIS Lookup
Look up a domain's registration data (registrar, creation and expiry dates, name servers and status) straight over the WHOIS protocol.
IP Lookup
Get approximate details about an IP address.
Reverse IP Lookup
Takes an IP address and finds the domain or host (PTR record) associated with it, with geolocation and provider. Free and no sign-up.
SSL Lookup
Get all the details you can about an SSL certificate.
Text & SEO
Text, content and SEO tools to write, optimize and publish faster.
Case Converter
Convert text to UPPERCASE, lowercase, Title Case, camelCase, snake_case, kebab-case and more instantly. Copy each format with one click. No sign-up.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text in paragraphs, sentences, words or lists, with optional HTML format. Copy or download instantly. No sign-up.
Slug / URL Generator
Turn any title into an SEO-friendly slug: strips accents and symbols, lowercases and joins with hyphens. Configurable separator and stop words. No sign-up.
Meta Tags & SERP Preview Generator
Build any page's meta tags (title, description, Open Graph and Twitter) with a Google-style result preview and length counters. No sign-up.
UTM Campaign URL Builder
Build links with UTM parameters (source, medium, campaign, term and content) to track your campaigns in Google Analytics. With suggestions and lowercasing. No sign-up.
Text Summarizer
Summarize long texts in seconds by picking the key sentences, right in your browser. Works in English and Spanish. Copy the result. Free and private.
Image
Compress, convert and edit images right in your browser, without uploading them to any server.
Favicon Generator
Create your site's favicon from an image or from text/emoji. Download the full pack (favicon.ico, PNGs, apple-touch-icon and site.webmanifest) with ready-to-use HTML. All in your browser.
Image Compressor
Compress and optimize JPG, PNG or WebP images without visible quality loss, with quality control, format change and resizing. All in your browser.
Image Converter
Convert images between WebP, JPG and PNG in batches, with quality control and individual or bulk download. All in your browser, nothing uploaded.
Image Resizer
Resize your images by pixels or percentage, keeping the aspect ratio, with format change and download. All in your browser, nothing uploaded.
Background Remover
Remove the background from any image with AI, right in your browser. Download a transparent PNG or swap the background for a color. Free and private.
Image to Text (OCR)
Extract text from an image or photo with OCR, right in your browser. Supports English, Spanish and more languages. Copy or download the result. Free and private.
Design & CSS
Visual CSS generators —gradients, shadows and effects— with live preview and ready-to-copy code.
CSS Gradient Generator
Create linear, radial and conic CSS gradients with live preview, unlimited color stops and ready-to-copy code. No sign-up.
WCAG Contrast Checker
Compute the contrast ratio between two colours and check it against WCAG AA and AAA, for text and interface elements. Suggests a fixed colour without losing the hue.
CSS Box Shadow Generator
Create CSS box-shadow effects with offset, blur, spread, color and opacity control, multiple layers, inset and live preview. No sign-up.
CSS Glassmorphism Generator
Create the frosted-glass (glassmorphism) effect in CSS with blur, transparency, saturation, border and radius, with live preview. No sign-up.
Data & Format
Convert, compare and transform data between formats —JSON, CSV, YAML, Markdown and more— right in your browser.
CFDI 4.0 XML Viewer
Open a CFDI 4.0 invoice XML and read it in plain language: issuer, recipient, line items, taxes and tax stamp, with SAT codes translated and the arithmetic checked.
JSON and CSV Converter
Convert JSON to CSV and CSV to JSON instantly, with a configurable delimiter, type detection and download. All in your browser, nothing uploaded.
XML and JSON Converter
Convert XML to JSON and JSON to XML in both directions, with control over attributes and indentation. All in your browser, nothing uploaded.
XML Formatter and Validator
Indent, minify and validate XML in your browser. It preserves comments, CDATA and the declaration, and points at errors with line and column.
JSON Diff
Compare two JSON documents structurally, not as text: key order and indentation stop counting as differences. Matches arrays by id and flags type changes.
Text Diff Checker
Compare two texts and highlight the differences line by line, with unified and side-by-side views and ignore case or whitespace. All in your browser.
Excel to JSON, CSV and SQL
Open an .xlsx in your browser and export it to JSON, CSV or SQL statements with CREATE TABLE. Detects dates and types, and the file never leaves your machine.
JSON and YAML Converter
Convert JSON to YAML and YAML to JSON instantly, with configurable indentation, download and copy. All in your browser, nothing uploaded.
Markdown and HTML Converter
Convert Markdown to HTML and HTML to Markdown instantly, with rendered preview, source code and download. All in your browser, nothing uploaded.
Number Base Converter
Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36 instantly, with arbitrary precision. All in your browser.
Utilities
Assorted calculators and generators for everyday work —dates, mock data and more— right in your browser.
Date and Age Calculator
Your exact age in years, months and days, the days between two dates, how many days 2 years and 5 months are, and which year you were born. No signup.
Mexican Test Data Generator
Generate fictitious RFC, CURP, CLABE and NSS with correct check digits to seed development environments and tests. Export to JSON, CSV or SQL. No server involved.
Mock Data Generator
Generate realistic mock data (names, emails, dates, UUIDs, numbers and more) with a configurable schema and export to JSON or CSV. All in your browser.
Cron Expression Validator
Validate and explain cron expressions in plain language, with a field breakdown and the next runs. Supports ranges, lists, steps and shortcuts. No sign-up.
robots.txt Generator
Build your site's robots.txt with per-robot rules (Allow, Disallow, Crawl-delay) and sitemaps, with quick templates. Copy or download instantly.
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Need a specific tool?
If you have a tool suggestion you would like to see here, feel free to contact me.
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