Free tools + honest guides for people who run everyone else's infrastructure.
One clean tab. No logins. No upsells. Every tool computes results in your browser unless we say otherwise. If you've ever wanted a version of jsonformatter.org that didn't try to sell you a course, this is it.
Web Dev
8 toolsThe utilities you reach for every day: JSON, YAML, Base64, regex, JWT, cron.
Web Dev
JSON Formatter and Validator
Paste JSON, get it pretty-printed or minified. Validates syntax, highlights errors, works entirely in your browser.
Web Dev
YAML ↔ JSON Converter
Convert YAML to JSON and back in your browser. Resolves anchors and merge keys, handles multi-document files, and lets you pick the output indent.
Web Dev
Base64 Encoder/Decoder
Encode and decode Base64 in your browser, with correct UTF-8 handling, a URL-safe alphabet toggle, and file mode for binary payloads.
Web Dev
URL Encoder/Decoder
Percent-encode and decode URLs with the right rules: component, full-URI, or form encoding, plus a query string parser and builder.
Web Dev
Regex Tester
Test JavaScript regular expressions with live match highlighting, a capture group table, replace preview, and ReDoS guardrails.
Web Dev
UUID Generator
Generate v4, time-ordered v7, and Nil UUIDs in bulk, in any format, and inspect an existing UUID for its version, variant, and embedded timestamp.
Web Dev
Timestamp Converter
Convert Unix seconds, milliseconds, microseconds, and nanoseconds to ISO 8601 and human-readable dates in any IANA timezone, with a live clock.
Web Dev
Markdown ↔ HTML Preview
Side-by-side Markdown editor with GitHub-flavored Markdown support, live preview, and a sanitized HTML pane you can copy.
DevOps
6 toolsConfig, cluster, and network tooling for the people running the pipelines.
DevOps
Cron Expression Builder
Validate standard and Quartz cron expressions, read them in plain English, and see the next 10 fire times in any IANA timezone.
DevOps
Kubernetes YAML Linter
Paste a manifest and get severity-ranked findings: removed apiVersions, missing requests and probes, unpinned images, and permissive securityContext.
DevOps
HTTP Status Code Reference
Searchable HTTP status reference with links to the RFC and common causes for each code.
DevOps
HTTP Header Inspector
Paste a URL, see the response headers with a plain-English explanation of each.
DevOps
curl Command Builder
Visual builder for curl commands. Fill in method, headers, and body — copy the exact command.
DevOps
Nginx and Caddy Config Generator
Fill in a domain and an upstream, get a working nginx server block and an equivalent Caddyfile side by side, with TLS, headers, and rate limiting.
Security
6 toolsCertificates, DNS hygiene, and password posture — for defensive use only.
Security
JWT Decoder
Decode a JWT header and payload. Optionally verify HS256/RS256 signatures — all client-side.
Security
TLS Certificate Inspector
Fetch a live certificate chain by hostname or paste a PEM. Decodes subject, SANs, validity, key and signature algorithms, fingerprints and embedded SCTs.
Security
Certificate Transparency Lookup
Every certificate ever logged for a domain, with a subdomain discovery view that dedupes SANs into a copyable hostname list and a CSV export.
Security
DNS Lookup
Query A, AAAA, CNAME, MX, TXT, NS, SOA, CAA and SRV records over DoH, with TTLs, the DNSSEC AD bit, and SPF, DMARC, MX and CAA read back in plain English.
Security
Password Strength and Breach Check
Local entropy estimate plus optional HIBP k-anonymity breach check. Your password never leaves the browser.
Security
Hash Generator
CRC32, MD5, SHA-1, SHA-256, SHA-384, SHA-512 and HMAC over text or a local file. Hex or base64 output, computed in your browser.
Recent guides
tls-certs
Why your ACME renewal quietly broke last month
Let's Encrypt changed its intermediates, dropped an EKU, killed OCSP, and started shortening lifetimes. None of it throws a renewal error. Here is what to check.
tls-certs
Certificate Transparency explained for devs
The plain-English explanation of Certificate Transparency logs — what they contain, who runs them, and why they matter for every domain you own or ship code to.
kubernetes
Cron syntax, actually explained
The five standard cron fields, the Quartz six and seven field variants, macros, step values, the day-of-month versus day-of-week OR rule, and the timezone traps.
tls-certs
How to find every subdomain with CT logs
Certificate Transparency logs are the most complete public record of a company's hostnames. How to query them, clean the output, and run it as a standing control.
web-dev
Every HTTP status code, and when it shows up
A working reference to the HTTP status codes you will actually meet in production, what each one really means, and the pairs everyone confuses.
tls-certs
JWT, decoded: parts, algorithms, pitfalls
What the three parts of a JWT contain, how the signing algorithms differ, which claims you must validate, and the practices RFC 8725 tells you to adopt.