Free online utilities

A growing collection of fast, no-nonsense tools for DNS, email deliverability, network diagnostics and everyday developer tasks. No ads, no sign-up, nothing stored.

DNS & Domain

DNS Lookup Dig-style lookup for A, AAAA, MX, TXT, NS, SOA, SRV, CAA, PTR — plus subdomain sweep. DNS Propagation Query one record across Google, Cloudflare, Quad9 and OpenDNS to spot propagation lag. WHOIS Lookup Registration, registrar, dates and nameservers for a domain (live WHOIS).

Email & Deliverability

SPF Checker Fetch and validate a domain's SPF record, with the 10-lookup limit in mind. DMARC Checker Read and explain a domain's DMARC policy (p, rua, pct, alignment). DKIM Checker Look up a DKIM public key by selector and domain. MX Lookup List a domain's mail servers in priority order. Blacklist Check Check an IP against major DNS blacklists (RBLs). Email Verifier Validate an address: syntax, domain MX, role/disposable, live mailbox probe. Email Header Analyzer Paste raw email headers to trace delivery hops and delays.

Network & Security

SSL Certificate Inspect a site's TLS certificate: issuer, validity, SANs and expiry. HTTP Headers View a URL's response headers and follow its redirect chain. Security Headers Grade a site on HSTS, CSP, X-Frame-Options and other security headers. Port Checker Test whether common or custom TCP ports are open on a host. IP Info Reverse DNS plus ASN, network and country for an IP (via Team Cymru).

Encoding & Data

JWT Decoder Decode a JSON Web Token to read its header and payload claims. HMAC Generator Compute an HMAC (SHA-256/512, SHA-1, MD5) from a key and message. Base64 Encode or decode Base64 text. URL Encode/Decode Percent-encode or decode URL/query strings. Hash Generator MD5, SHA-1, SHA-256, SHA-512 and CRC32 of any text. JSON Formatter Pretty-print, validate or minify JSON. Punycode / IDN Convert internationalized domains between Unicode and punycode (xn--).

Developer Tools

Regex Tester Test a regular expression against sample text and see the matches. Password Strength Estimate how strong a password is: entropy and crack-time. Bcrypt Hash & Verify Generate a bcrypt password hash, or verify a password against one. Cron Explainer Translate a cron expression into plain English and list its next run times. UUID Generator Generate random UUID v4 values in bulk. Password Generator Create strong random passwords with adjustable rules. Subnet Calculator IPv4 CIDR maths: network, broadcast, mask, host range and count. Epoch Converter Convert between Unix timestamps and human dates.

Text & Conversion

Color Converter Convert colours between HEX, RGB and HSL with a live preview. Case Converter Convert text between UPPER, lower, Title, camelCase, snake_case and kebab-case. HTML Entity Encoder Encode or decode HTML entities like & and ©. Number Base Converter Convert numbers between binary, octal, decimal and hexadecimal. Text Compare Compare two blocks of text and highlight the differences line by line. Word Counter Count words, characters, sentences, paragraphs and reading time. Slugify Turn a title into a clean, URL-friendly slug. Lorem Ipsum Generate placeholder Lorem Ipsum paragraphs, sentences or words.

Frequently asked questions

Are these tools free to use?

Yes. Every tool on this site is completely free, with no sign-up, no account and no usage limits beyond basic anti-abuse rate limiting. There are no ads.

Do you store the domains, IPs or text I look up?

No. Nothing you enter is written to a database or a file. Queries run in memory and results are returned straight to your browser. There is no tracking.

What can I do with these utilities?

You can diagnose DNS and email deliverability problems (SPF, DKIM, DMARC, MX, blacklists), inspect SSL certificates and HTTP headers, check open ports, and run everyday developer conversions like Base64, hashing, JSON formatting and subnet maths.

Do I need to install anything?

No. Everything runs in your browser against our server — there is nothing to download or install, and it works on desktop and mobile.