Free tools for developers

The most-searched category on DevTools Hub — URL encoding, decoding, and Base64 conversions.

Generate a strong password, check how one holds up, and set or validate the policy your team follows.

Validate, lint, and visualize Docker Compose files — and make sense of container networking.

Build, test, visualize, and debug regular expressions — with a cheat sheet when you need a quick reference.

Independent tools for the test data every project eventually needs — unique IDs and placeholder text. All run entirely in your browser.

Format, validate, diff, minify, convert, query, and schema-generate/validate JSON — ten tools for the format everything speaks. All run entirely in your browser.

Base64, URL, HTML, hex, and ASCII encoding and decoding, plus query string and full URL parsing, building, inspection, Unicode analysis, and string-literal escaping — sixteen tools for the encodings that show up constantly in web development. All run entirely in your browser.

Timestamps, timezones, and cron schedules — five tools for the two date-and-time problems every backend eventually runs into. All run entirely in your browser.

Everything for working with JSON Web Tokens, in one place — decode, understand, verify, build, and secure them. All eight tools run entirely in your browser; nothing you paste is ever sent anywhere.

MD5, SHA, checksums, HMAC, and password hashing — ten tools for hashing text, verifying files, and signing messages. All run entirely in your browser.

Build, test, visualize, debug, and escape for JavaScript regular expressions — six tools covering the whole regex workflow. All run entirely in your browser.

Format, validate, minify, diff, index-advise, and explain SQL — six tools covering readability, correctness, schema changes, and performance. All run entirely in your browser.

View, validate, diff, and put an OpenAPI/Swagger document to work — five tools covering the full spec lifecycle. All run entirely in your browser.

Validate, lint, format, visualize, merge, and resolve Docker Compose files, and lint Dockerfiles — seven tools covering the whole Docker workflow. All run entirely in your browser.

Validate, visualize, lint, and audit secrets in GitHub Actions workflows — four tools covering correctness and security. All run entirely in your browser.

Validate, diff, resolve, and convert .env files — five tools for the dotenv format's real parsing rules and the gotchas that fail silently. All run entirely in your browser.

Validate, format, calculate resources, diff, explore relationships, and merge or compare Helm values for Kubernetes manifests — seven tools covering correctness, readability, and resource planning. All run entirely in your browser.

Validate and format YAML — syntax errors, duplicate keys, parser-version gotchas, and consistent indentation — schema-agnostic, for any YAML file. All run entirely in your browser.

Parse and build ARNs, generate, review, simulate, and minify IAM policies, validate tag policies, look up Regions, and validate CloudFormation templates — nine tools for everyday AWS work. All run entirely in your browser.

Format and validate GraphQL queries, mutations, and SDL schemas with the real reference parser. All run entirely in your browser.

Computer science fundamentals for practicing engineers — algorithm complexity, performance analysis, and scalability, with interactive tools and practical examples. All run entirely in your browser.

How the structures underneath every algorithm actually work — arrays, hash tables, trees, and more, visualized step by step. All run entirely in your browser.

The numbers behind systems that hold up under load — caching, capacity, and the metrics worth actually tracking. All run entirely in your browser.

Tools for the problems that show up once a system spans more than one machine — unique IDs, coordination, and consistency. All run entirely in your browser.

Generate a strong password, check the strength of one you already have or estimate one hypothetically, define or validate the policy an organization follows, and grade its storage practices. All run entirely in your browser.

Encrypt and decrypt text with AES, generate or inspect RSA and SSH keys, audit authorized_keys, build SSH config blocks, and build or decode certificate signing requests — entirely in your browser using the native Web Crypto API.

Work out Linux file permissions, review sudo and firewall configuration, and generate a full server hardening checklist. Runs entirely in your browser.

Work out IPv4 subnets, validate SPF email records, and score a website's HTTP security headers. Runs entirely in your browser.

Validate WireGuard and OpenVPN configs, compute split-tunnel routes, check IPsec/IKEv2 cipher proposals, and work out the right MTU — five tools covering setup, hardening, and the fragmentation problems that show up after. All run entirely in your browser.

VPN MTU / TCP MSS Calculator

Compute a recommended VPN interface MTU and TCP MSS clamp for WireGuard, OpenVPN, or IPsec.

IPsec/IKEv2 Proposal Strength Checker

Break down an ike=/esp= cipher proposal string and flag weak ciphers, digests, and DH groups.

VPN Split-Tunnel CIDR Calculator

Compute the AllowedIPs/route list to send everything through a VPN except specific subnets.

OpenVPN Config Auditor

Audit an .ovpn client config — deprecated ciphers, weak digests, missing tls-crypt, and VORACLE-vulnerable compression.

WireGuard Config Validator

Validate a WireGuard .conf file — malformed keys, missing AllowedIPs, duplicate peers, and bad endpoints.

fail2ban Jail Config Validator

Validate a fail2ban jail.local file — ineffective ban times, risky ignoreip ranges, and disabled jails.