# bytesdust tools

> Static network utilities from bytesdust (https://bytesdust.com). Everything runs in the browser or on Cloudflare's edge — no server-side logic. Most tools are fully offline; the few third-party or user-directed network calls are button-gated and documented per tool below.

## Tools

- [Subnet Calculator](https://tools.bytesdust.com/subnet-calculator/): IPv4 CIDR calculator — network, broadcast, usable hosts, masks, binary view — plus IP-range-to-CIDR summarization (minimal covering block list). IPv6 analyzer: expand/compress, address-type detection (ULA, link-local, 6to4, Teredo, IPv4-mapped…), embedded IPv4, and BigInt subnet math (network, first/last address, total counts as powers of two). State is encoded in the URL (?cidr=..., ?v6=..., ?range=...) so results are shareable.
- [IP Info](https://tools.bytesdust.com/ip-info/): public IP, country, Cloudflare colo (decoded to city), edge latency, scheme, SNI, TLS version and key exchange, HTTP version, WARP and Gateway status via the same-origin /cdn-cgi/trace endpoint. Button-gated external lookups: PTR (reverse DNS), ASN (Team Cymru via DoH), RDAP/WHOIS, and WebRTC public-IP leak check. Each lookup runs only when its button is pressed; a debug panel shows per-query timing, endpoint, HTTP status and errors. Local WebRTC addresses need no network call. No global consent checkbox.
- [DNS Lookup](https://tools.bytesdust.com/dns-lookup/): any of 16 DNS record types (A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, SRV, PTR, NAPTR, TLSA, DS, DNSKEY, SVCB, HTTPS) for any hostname via DNS-over-HTTPS to a visitor-selected resolver (cloudflare-dns.com, DNS4EU, Rethink DNS, CleanBrowsing, doh.dns.sb, freedns.controld.com, or a custom RFC 8484 endpoint such as the visitor's own NextDNS URL), only when the Lookup button is pressed. Bulk mode queries a newline-separated list of hostnames (capped at 30, limited concurrency). All-types mode queries every supported record type at once. State in the URL (?host=..., ?type=..., ?bulk=1, ?all=1, ?provider=..., ?endpoint=...).
- [JWT Decoder](https://tools.bytesdust.com/jwt-decoder/): decodes a JWT's header and payload and evaluates its exp/nbf claims, entirely client-side. Not a verifier — no signature checking, nothing ever sent anywhere.
- [Hash & Encoding](https://tools.bytesdust.com/hash-encoding/): 46 hash algorithms (SHA-2 including SHA-512/t, SHA-3/Keccak, BLAKE, CRC, Adler, xxHash, MurmurHash3, MD4/MD5, NTLM, RIPEMD, GOST R 34.11-94, Streebog and more) via WebAssembly and in-house implementations, and URL encode/decode, computed locally as you type; JSON/TXT/CSV/multihash export.
- [File Hash Calculator](https://tools.bytesdust.com/file-hash/): 45 hash algorithms (MD5, SHA-2, SHA-3, BLAKE2/3, RIPEMD, Whirlpool, SM3, GOST, Streebog, CRC, xxHash, MurmurHash3 and more) for a dropped or chosen file, streamed in chunks entirely on-device; JSON/TXT/CSV/multihash export and coreutils checksum files.
- [MAC Address Lookup](https://tools.bytesdust.com/mac-lookup/): identifies a MAC address's vendor from a bundled IEEE OUI registry snapshot (24/28/36-bit), and flags multicast / locally-administered (randomized) addresses. Fully offline.
- [HTTP Ping](https://tools.bytesdust.com/http-ping/): samples round-trip latency to any URL from the visitor's own browser (no-cors fetch timing) — min/avg/jitter over 8 samples, no server in between.
- [User-Agent Parser](https://tools.bytesdust.com/user-agent-parser/): decodes any User-Agent string into browser, engine, OS and device type via local pattern matching. Pre-filled with the visitor's own UA, editable for any pasted string. Fully offline.
- [Email Header Analyzer](https://tools.bytesdust.com/email-headers/): paste raw email headers, or upload an .eml/.txt file, to see the Received hop chain with per-hop delays, and SPF/DKIM/DMARC verdicts as already reported by the verifying server (not re-verified against DNS). Fully offline text parsing, file read client-side.
- [TLS Certificate Decoder](https://tools.bytesdust.com/cert-decoder/): decodes a PEM/X.509 certificate (issuer, subject, validity, public key, SANs, extensions, SHA-1/SHA-256 fingerprints) via a hand-written DER/ASN.1 reader, verified against openssl x509 -text output. Paste PEM text or upload a .pem/.crt/.cer file. Fully offline.
- [Security Headers Analyzer](https://tools.bytesdust.com/security-headers/): paste HTTP response headers (or upload a .txt capture) to grade a site's security posture — CSP directive-by-directive (unsafe-inline/unsafe-eval/wildcards), HSTS, X-Content-Type-Options, Referrer-Policy, frame protection — with an A–F score and concrete fix suggestions. Fully offline; analysis runs on paste.
- [Cron Parser](https://tools.bytesdust.com/cron-parser/): decodes a 5-field cron expression (names, steps, ranges, lists; dom/dow OR rule) into a plain-English description, a per-field breakdown, and the next 10 run times in the visitor's local timezone. State in the URL (?expr=...). Fully offline.
- [Unix Timestamp Converter](https://tools.bytesdust.com/unix-timestamp/): converts Unix timestamps (seconds, milliseconds, microseconds, nanoseconds — unit auto-detected by magnitude, overridable) to UTC ISO 8601, RFC 2822, any IANA time zone and relative time; the reverse direction parses ISO 8601 dates; a live clock shows the current seconds and milliseconds with pause. State in the URL (?ts=..., ?tz=..., ?iso=...). Fully offline.
- [Base64 Encode / Decode](https://tools.bytesdust.com/base64/): UTF-8 Base64 encode/decode, standard (+/) or URL-safe (-_) alphabet, optional padding, byte counts; the decoder accepts both alphabets (and reports which one it recognised), ignores whitespace and rejects invalid input with a precise message. State in the URL holds only the options (?mode=..., ?alphabet=..., ?padding=...), never the text. Fully offline.
- [IPv6 Subnet Calculator](https://tools.bytesdust.com/ipv6-subnet-calculator/): parse any IPv6 address with prefix (compressed, full, IPv4 tail), show RFC 5952 compressed and expanded forms, address type, network first/last address and exact BigInt address counts, ip6.arpa reverse names, and split a prefix into smaller subnets (e.g. a /48 into 65,536 /64s) with paging. State in the URL (?cidr=..., ?split=...). Fully offline.
- [SPF, DKIM & DMARC Generator](https://tools.bytesdust.com/email-auth-records/): build the three email-authentication TXT records with guided options — SPF mechanisms with RFC 7208 DNS-lookup counting, DKIM key formatting (PEM or bare Base64, split at 255 characters; the key is never sent or stored), DMARC policy with alignment, pct and reporting addresses — plus the record name to create and per-option explanations. State in the URL holds the options, never the DKIM key. Fully offline.
- [chmod Calculator](https://tools.bytesdust.com/chmod-calculator/): convert Unix permissions between octal (755), symbolic (rwxr-xr-x) and a checkbox matrix (with setuid/setgid/sticky), apply chmod symbolic expressions (u+x,g-w,o=r), convert umasks to the resulting file and directory permissions, and copy a ready chmod command. State in the URL (?mode=...). Fully offline.
- [Fingerprint Observatory](https://tools.bytesdust.com/fingerprint/): everything the browser exposes — passive signals, canvas/WebGL/audio/fonts, hardware, JS engine, codecs, permissions, extensions, crypto wallets — computed locally via a modular probe framework, with a composite fingerprint hash and JSON export. Optional third-party network probes (WebRTC STUN, Cloudflare meta, NextDNS, ipinfo.io) run only after explicit user consent; advanced probes (localhost port scan, extension probing) are individually opt-in.

## Categories

- [Network tools](https://tools.bytesdust.com/network/): subnet math, DNS, TLS certificates, latency and MAC lookups — in the browser or button-gated.
- [Dev tools](https://tools.bytesdust.com/dev/): JWT, hashes, cron, timestamps, Base64, User-Agent, security headers — offline in the browser.
- [Privacy tools](https://tools.bytesdust.com/privacy/): what your browser reveals about itself, computed locally.

## Machine-readable endpoint

- https://tools.bytesdust.com/cdn-cgi/trace — Cloudflare edge feature, key=value text: ip, loc, colo, tls, http, uag, warp, sni.

## Notes

- Every tool above except Fingerprint Observatory can export its current result as a JSON file (Fingerprint Observatory has its own, separate JSON export).
- Fully static site (Astro, output: "static") hosted as Cloudflare Workers static assets.
- 404: https://tools.bytesdust.com/404/
- Sitemap (every page in one list, grouped by category): https://tools.bytesdust.com/sitemap/
- Sitemap for crawlers: https://tools.bytesdust.com/sitemap-index.xml
- Main site: https://bytesdust.com (Hugo blog — cloud, code, containers).