All Tools

76 free tools for developers and sysadmins. Click any to start — no signup required. Most run entirely in your browser.

API & Network

Send HTTP requests via sandboxed proxy

Public URL for receiving webhooks live

Define endpoints with custom responses

cURL → Python / JS / PHP / Go

Cloud Cost Calculator

Compare AWS, Azure, GCP, Logicloud pricing

Data Tools

Format, minify, validate, convert

CSV/Excel/JSON → JSONL for AI datasets

Schema Validator

Validate JSON against JSON Schema

Run SQL on in-browser SQLite

Regex Playground

Test patterns with live matches

Compare text side-by-side

Security & Auth

Decode and inspect JWT tokens

Generate CSR + private key in browser

Encode / Decode

Base64, URL, HTML, Hex

DNS & Email Auth

A, MX, TXT, CNAME, NS records

Check mail servers and connectivity

Check and generate SPF records

Check and generate DKIM records

Check and generate DMARC policies

Check certificate expiry & details

Geolocation, ASN, PTR for any IP

Developer Utilities

Build and explain cron expressions

Markdown Editor

Write, preview, export Markdown

Format and minify CSS

Convert, compress, resize images

Format JSON, SQL, CSS, HTML, JS, TS

SEO

Schema JSON-LD Generator

Article, Product, FAQ, LocalBusiness, Org, Breadcrumb, Event, Review, Recipe

Meta Tag Analyzer

Audit title, description, canonical, robots, OG for any URL

Google SERP Snippet Preview

Pixel-accurate title + description truncation preview

robots.txt Tester

Is my URL allowed by robots.txt? Which rule matched?

robots.txt Generator

Build a robots.txt from rules with CMS presets

XML Sitemap Validator

Validate sitemap.xml structure, list URLs, report errors

XML Sitemap Generator

URL list → sitemap.xml with priority + changefreq

Redirect Chain Checker

Trace 301/302 hops, catch loops and soft-404s

OG / Twitter Card Validator

Extract OG + Twitter tags, preview FB / LinkedIn / X shares

Hreflang Generator

Locale + URL matrix → hreflang tags with reciprocity guidance

Keyword Density Analyzer

1/2/3-gram frequency + stopwords; paste text or URL

Keyword Cannibalization Checker

Find pages competing for the same query (TF-IDF cosine similarity)

Heading Structure Checker

H1-H6 outline; flag missing H1, multiple H1s, skipped levels

Image Alt Auditor

Find images with missing or empty alt text

Canonical Tag Checker

Verify canonical URL presence, uniqueness, self-reference

Hreflang Checker

Validate hreflang — reciprocity, x-default, self-reference

Word Count & Content Ratio

Word count, text-to-HTML ratio, thin-content verdict

Structured Data Detector

Find JSON-LD, Microdata, RDFa on any page

List all internal and outbound links with anchor + rel

Broken Link Checker

Check the first 100 outbound links for 4xx/5xx/errors

HTTP Headers Checker

Full HTTP response headers and status for any URL

Canonicalization Checker

Test all 4 variants (www/non-www x http/https) canonicalise to one

Security & Cache Headers

HSTS, CSP, X-Frame, cache-control — full security header audit

Meta Robots / X-Robots Checker

Extract meta robots directives + HTTP X-Robots-Tag header

Mixed Content Checker

Find http:// resources loaded on https:// pages

Meta Tag Generator

Generate title, description, canonical, OG, Twitter tags

Keyword Combiner

Permute 3 seed lists into every keyword combination

Text / Word / Char Counter

Character, word, sentence, paragraph counts + reading time

Convert any string to URL-safe slug (kebab, snake, camel, dot)

UTM Campaign Builder

Build tracked URLs for Google Analytics utm_source, medium, campaign

Readability Score

Flesch, Flesch-Kincaid, Gunning Fog, SMOG, ARI, Coleman-Liau

PageSpeed & Core Web Vitals

Google Lighthouse: LCP, FCP, TBT, CLS, plus perf/SEO/a11y scores

Mobile-Friendly Check

Viewport, tap targets, font size, content width via Lighthouse

Safe Browsing Check

Google Safe Browsing v4 — flagged for malware, phishing, unwanted?

GEO — AI Answer Engines

llms.txt Generator

Build a spec-valid llms.txt for AI crawlers

llms.txt Checker

Fetch and validate a site's llms.txt + llms-full.txt

AI Bot Access Checker

GPTBot, ClaudeBot, Google-Extended, PerplexityBot — allowed or blocked?

Answerability Score

Score how well your page answers AI queries — with prioritized fixes

GEO Readiness Checklist

30+ item self-assessment across strategy, content, technical, measurement

Cite-Worthiness Score

How quotable is your page for AI answers? 14 heuristic checks

Citable Sources Scanner

Flag claims that need citations

AI-Answer Formatter

Restructure content into TL;DR + Q&A + bullets for AI ingestion

llms.txt Auto-draft from Sitemap

Fetch your sitemap and generate a ready-to-edit llms.txt

llms-full.txt Builder

Fetch up to 25 pages, convert each to Markdown, assemble llms-full.txt

AI Meta / X-Robots Generator

Control AI training — noai, noimageai, max-snippet, noarchive

Content Freshness Checker

Extract publication dates and score how stale the content is

Compress any content into an AI-quotable summary of N words

URL to Clean Markdown

Fetch any page, convert to clean Markdown (for RAG or llms-full.txt)

RAG Chunk Previewer

See how content splits into retrieval chunks (tokens/paragraphs/headings)

Entity / Key-Topic Extractor

Find named entities (people, orgs, places, products) and key topics