Thoughtfully Crafted Developer Tools
A collection of fast, privacy-friendly developer, DevOps, networking, security, and text utilities that run directly in your browser.
Privacy-first
Everything runs client-side - nothing you paste is ever uploaded.
Fast by default
No sign-up, no loading spinners waiting on a server round-trip.
Always expanding
New developer tools are added regularly, so there's more to explore every time you visit.
Security
Redact, decode, and generate the things that keep systems safe.
Log Sanitizer
Mask secrets, tokens, and PII in logs before you share them.
Secret Scanner
Scan pasted text or files for leaked credentials and keys.
JWT Decoder
Inspect a JSON Web Token's header, payload, and signature.
JWT Generator
Build and sign a JWT for testing.
Password Generator
Generate strong, random passwords with custom rules.
Hash Generator
Compute MD5, SHA-1, SHA-256, and SHA-512 hashes.
SSL Certificate Viewer
Decode a PEM certificate's subject, issuer, and validity.
HTTP Security Headers Analyzer
Analyze HTTP response headers for security configuration issues.
DevOps
Validators and testers for the configs behind every deploy.
Regex Tester
Test regular expressions against sample text live.
Cron Builder
Build and explain cron expressions in plain English.
Docker Compose Validator
Validate a docker-compose.yml against the schema.
Kubernetes YAML Validator
Validate Kubernetes manifests before you apply them.
Nginx Config Validator
Check nginx.conf syntax before deploying it.
JSON & Data
Format, compare, and convert structured data.
JSON Formatter
Format, validate, beautify, minify, and explore JSON instantly.
JSON Diff
Compare two JSON documents and highlight differences.
YAML to JSON
Convert YAML to JSON and back.
XML Formatter
Format and validate XML documents.
Networking
Look up, calculate, and parse network-facing data.
CIDR Calculator
Calculate subnet info from an IPv4 CIDR block.
DNS Lookup
Query A, AAAA, MX, TXT, and other DNS records.
IP Calculator
General-purpose IPv4 address and subnet calculator.
WHOIS Lookup
Look up domain registration details.
Subnet Mask Calculator
Convert between prefix length, subnet mask, and wildcard mask.
Port Checker
Look up what a well-known port number is used for.
User Agent Parser
Break a User-Agent string into browser, OS, and device.
Encoding
Convert text between the formats systems actually speak.
Utilities
Small, focused helpers for everyday development tasks.
UUID Generator
Generate v4 (random) or v7 (time-ordered) UUIDs in bulk.
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates.
Lorem Ipsum Generator
Generate placeholder text by word, sentence, or paragraph.
Slug Generator
Turn any string into a clean URL slug.
Popular tools
The most frequently used tools in the collection right now.
Log Sanitizer
Mask secrets, tokens, and PII in logs before you share them.
HTTP Security Headers Analyzer
Analyze HTTP response headers for security configuration issues.
JSON Formatter
Format, validate, beautify, minify, and explore JSON instantly.
CIDR Calculator
Calculate subnet info from an IPv4 CIDR block.
From the Learning Center
Practical guides on networking, security, and logging.
CORS Explained: Access-Control-Allow-Origin, Credentials and Common Mistakes
CORS is a browser-enforced exception to the same-origin policy. Here's how it works and the one combination that goes wrong constantly.
What Is HSTS? Strict-Transport-Security Explained
HSTS closes a narrow but real window for downgrade attacks. Here's exactly what it enforces and how to configure it.
Content-Security-Policy (CSP) Explained With Examples
CSP is an allow-list for where your page's resources can load from. Here's how the directives fit together.
Frequently asked questions
- What is DevCraftKit?
- DevCraftKit is a free collection of online developer tools covering security, DevOps, networking, JSON, encoding, and everyday utilities. Tools run in your browser, so results are instant and nothing you enter is uploaded.
- Are the tools on DevCraftKit really free?
- Yes - every tool is free to use, with no account, sign-up, or usage limit.
- Is my data safe when I use these tools?
- Yes. Most tools process everything locally in your browser, so pasted text, files, and generated values are never uploaded to a server.
- How often are new tools added?
- New developer tools are added regularly, expanding coverage across development, networking, cloud, DevOps, security, data, and system administration.
- Do I need to create an account?
- No account is required for any tool. Just open the tool and start using it.
Enjoying DevCraftKit?
These developer tools are free to use. If DevCraftKit saves you time, consider buying me a byte 💾. Every bit of support helps keep the project growing.