DevOps tools that run in your browser
Small utilities I got tired of searching for. Every one of them is pure client-side JavaScript — no sign-up, no backend, and nothing you paste ever leaves your machine.
Visual Subnet Calculator
Split and join CIDR blocks visually
Divide a network into subnets by clicking, then join them back. Shows address ranges, usable IPs, netmasks and host counts — and encodes your whole division into a shareable link. Look up a single address to see every network it belongs to and which reserved block it falls in.
Traceroute Analyzer
See how far your traffic actually gets
Paste traceroute, tracert or mtr output and get a straight answer: the last hop that replied, whether the destination was ever reached, and whether the silence after it is a firewall, a filtered router or real packet loss.
Network Lens
See what your Linux machine knows about its network
Run one read-only Bash script on a Linux host and drop the JSON it produces here. Network Lens turns it into a picture: how the machine reaches the internet, what it is listening on, who it is talking to, and what the collector could not see. The report is read in this tab and never uploaded.
PCAP Conversation Analyzer
See which hosts are talking, and about what
Drop in a capture from tcpdump, tshark or Wireshark and get the picture those tools bury in a packet list: a map of who talked to whom, how much moved in each direction, which services were involved and which connections never completed. The file is read in this tab — it is never uploaded.
Base64 Encoder / Decoder
Encode and decode, UTF-8 safe
Convert text to and from Base64, including URL-safe output. Handles full UTF-8 correctly, so emoji and non-Latin scripts survive the round trip.
Key & Certificate Inspector
Does this private key match this certificate?
Paste a certificate, a private key, a public key or a CSR — together or one at a time — and find out what algorithm it uses, how big it is, when it expires, and whether the key and the certificate actually belong to each other. Everything is parsed in this tab, which is the only sane place to paste a private key.
JWT Decoder
Inspect header, payload and expiry
Decode a JSON Web Token and read its header and claims, with human-readable timestamps and a live expiry check. Decoding only — the signature is never verified and the token never leaves the page.
YAML ↔ JSON Converter
Convert manifests both ways
Translate between YAML and JSON in either direction, with clear parse errors. Built for Kubernetes manifests, CI configs and Terraform variable files.
Cron Expression Explainer
Read a schedule in plain English
Translate a 5-field cron expression into a sentence and preview the next run times. Understands ranges, steps and lists, plus the usual @daily style shorthands.
UUID & Password Generator
Cryptographically secure values
Generate RFC 4122 v4 UUIDs and strong random passwords or API keys using the browser’s Web Crypto API — real entropy, not Math.random().
Why these run locally
Plenty of online converters and decoders quietly ship your input to a server. That is a bad habit to build when the thing in your clipboard is a Kubernetes secret or a production JWT. Everything here is implemented in the JavaScript that ships with the page: you can read the source, disconnect your network, and the tools still work.
Ideas for tools worth adding? Tell me — the list is deliberately easy to extend.