Developer utilities · Productivity

Quick Notes

A notepad that lives in your browser. Jot down notes, save links, keep a to-do list and set yourself reminders — no account, and nothing leaves this device.

⚡ Quick & easy 🔒 Private 💾 Saved in this browser

My Notes

0 saved

Important to know

Notes live in this browser on this device only. They do not sync to your phone or another browser — export a JSON file and import it there instead.

Not for secrets

Local storage is readable by anyone using this browser profile. Do not keep passwords, keys or payment details here.

Clear all notes

Permanently delete every note and task from this browser.

Questions

Are my notes stored on your server?

No. They are saved only in your browser's local storage. QuickDeveloperTools never receives, reads or shares them.

Will my notes stay after I close the browser?

Yes, as long as you use the same browser on the same device and do not clear its site data. Private/incognito windows forget everything when closed.

Can I move my notes to another device?

Use Export to download a JSON file, then Import it on the other device. Imported notes are added to what is already there; duplicates are skipped.

Do reminders send notifications?

No. A reminder is a date on the note; notes that are due or overdue are highlighted and can be sorted to the top, but nothing pops up when the page is closed.

Is it free?

Yes, free and without signup.

What else can you check?

These tools all work on the same connection and address data — pick whichever question you actually have.

Want to see the full path to a site? DNS, redirects, every hop, the CDN, TLS and the origin server. Want to know your public IP? See your IPv4 and IPv6 addresses, location, ISP and ASN. Want to check your tower & route? Live ping, speed, DNS, traceroute and a map of nearby points. Want to ping from around the world? Real latency from real probes across 12 countries, live on a map. Want to locate any IP address? City, region, country and coordinates for any public IP. Want to know if an IP is risky? Proxy, VPN, Tor, hosting and abuse-report indicators. Want to know if you're blacklisted? Check an address against major spam and abuse DNSBLs. Want to know who owns an IP? Network owner, ASN, CIDR range and abuse contact. Want to explore an AS number? Announced prefixes, BGP neighbours and registry details. Want to test your connection speed? Measure real download, upload, ping and jitter. Want to see what changed? Word-level diff between two blocks of text or code. Want to know if a DNS change is live yet? Compare answers from five independent public resolvers. Want to verify a domain's nameservers? Direct authoritative checks, glue records and SOA serials. Want to check a domain's DNSSEC setup? DNSKEY, DS records, signature expiry and real validation. Want to see the hop-by-hop path to a server? A real traceroute from a genuine probe anywhere in the world. Want to know if a server port is open? A real TCP connection attempt - open, closed or filtered. Want to measure latency to a server? Real connect timing - min/avg/max, jitter and connection loss. Want a clean URL slug from a title? Real transliteration, stop words and batch mode. Want to find and replace across a document? Regex, capture groups and a live preview before you commit. Want to find the invisible character? Code points, escapes, bytes and hidden-character detection. Want to escape text for HTML? Minimal, named or numeric entities, attribute-safe. Want to strip emoji cleanly? Whole clusters - no half-flags or stray modifiers left. Want to spot repeated words? Frequency, density and accidental doubles like "the the". Want to know if a URL is cached? Two requests prove whether your CDN is really caching it. Want to see what a site knows about you? Storage, cookies, tokens and what your browser actually cached. Want to run that check on any site? One-click bookmarklet reads storage and tokens where they live. Want to know who your site talks to? Renders the page and names every outside company it contacts. Is your site one address or four? www, non-www, http and https - which serve, which redirect. Need to build an Authorization header? Basic, Bearer, API key, Digest and AWS SigV4 - signed in your browser. Want to tidy up a messy SQL query? Beautify, minify, lint and convert keyword casing for six dialects. Need to work out a percentage? Nine calculators covering every way a percentage gets asked. Want to work out a rise or a raise? Increases, growth, compounding and CAGR, with the working shown. Want to work out a discount or a drop? Discounts, stacked sales and depreciation, with the working shown. What is actually on that page? Words, reading time, readability, every image, embed and link. Need a favicon that works everywhere? Every size, a real multi-resolution .ico, and the tags to paste. What headers does a site send back? Every response header on every redirect hop, explained. Need to test a regular expression? Live matches, capture groups, replace preview and code snippets. Need a JPG as a PNG? Batch convert in your browser, with optional transparent background. Need just some pages of a PDF? Split by page, range or chunk, or extract the pages you pick. What is hiding inside that image? EXIF camera settings, GPS tags, colour palette and web checks.