Curated tools, utilities, and resources to boost your development workflow, free and built for engineers.
Free-Threaded Python (No-GIL) Compatibility Scanner
Paste your Python code and find the shared counters, caches, and lazy singletons that are safe under the GIL but race under free-threaded Python 3.13t/3.14t. Each finding explains why it was safe with the GIL, what breaks without it, and how to fix it. Runs entirely in your browser.
Free Client-Side Risk Scanner for AI-Generated Code Diffs
Paste a git diff or patch and get an instant, free risk scan for the patterns AI coding agents slip in fastest: hardcoded secrets, disabled TLS checks, eval/exec injection, string-built SQL, and oversized deletions. No login, no upload, runs entirely in your browser.
Interactive CSS @scope Playground
Edit HTML and CSS side by side and watch the CSS @scope root and scope limit highlight live on the rendered page. Load preset examples, toggle @scope on and off to see style leakage, and copy the snippet. Runs entirely in your browser.
GraphQL Query Depth & Complexity Analyzer
Paste a GraphQL query and get its real depth and complexity score, computed by parsing the query, not by hand-counting fields. Flags unbounded list fields and shows which fields cost the most. No install, runs entirely in your browser.
MongoDB Aggregation Pipeline Explainer, No Database Needed
Paste a MongoDB aggregation pipeline array and get a plain-English, stage-by-stage walkthrough of what each stage does to your data, plus warnings for common performance mistakes. No live database connection required, runs entirely in your browser.
Electron vs Tauri vs Deno Desktop Decision Tool
Answer a few questions about your team's skills and your app's constraints, get a direct recommendation between Electron, Tauri, and Deno Desktop, with the specific tradeoff that drove the answer.
Fast Client-Side Rust Minimum Version Estimator
Paste a Rust source file or Cargo.toml and get an instant estimate of the minimum Rust version it actually needs, without installing and testing against a dozen toolchains.
Rust Box vs Rc vs Arc vs RefCell Decision Tool
Answer a few questions about your Rust ownership situation and get the exact smart pointer to reach for (Box, Rc, Arc, RefCell, or a combination like Arc<Mutex<T>>) with working code using your own type name. No install, runs entirely in your browser.
Static Flaky-Test Pattern Scanner for Playwright & Cypress
Paste a Playwright or Cypress test and get the known flaky-test anti-patterns flagged before it ever runs in CI: networkidle waits, late route registration, hard-coded sleeps, and strict-mode locators. Free, no CI history needed, runs entirely in your browser.
ARIA Live Region Announcement Queue Simulator
Paste HTML with aria-live regions, trigger content updates, and watch a simulated announcement queue show exactly what a screen reader would speak, in what order, and whether an assertive update interrupts a polite one still queued. No screen reader install needed, runs entirely in your browser.
Docker Compose to Podman Quadlet Converter
Paste your docker-compose.yml, get ready-to-use Podman Quadlet files (.container, .network, .volume) with a conversion coverage report, entirely in your browser.
Kubernetes Pod Crash Diagnostic Wizard
Answer a few questions about your crashing pod and get the exact diagnosis, the kubectl commands to confirm it, and the fix. Covers CrashLoopBackOff, OOMKilled, ImagePullBackOff, Pending, Evicted, and stuck states.
Paste a Crontab Line, Get .timer and .service Files
Paste a crontab line (or @daily / @reboot macro) and instantly get a ready-to-save systemd .timer and .service unit pair, a plain-English schedule, and the next 5 run times. No install, no upload, runs entirely in your browser.
Paste an npm Install Error, Get a Plain-English Fix
Paste your full npm ERESOLVE error and instantly see the two conflicting packages, the versions they each want, and a ready-to-paste overrides block for npm or resolutions block for Yarn. No install, no upload, runs entirely in your browser.
Docker Compose depends_on and Healthcheck Validator
Paste your docker-compose.yml and instantly see which services are missing condition: service_healthy, which healthchecks rely on a binary that might not be installed, and any circular dependencies, with a visual startup graph. No install, no upload, runs entirely in your browser.
Detect Risky npm postinstall/preinstall Scripts
Paste your package.json (or several dependency package.json files at once) and instantly see every preinstall, install, and postinstall script, risk-scored against real 2026 supply chain attack patterns like Shai-Hulud. No install, no upload, runs entirely in your browser.
Framework, Proxy, and Client Compatibility Reference for RFC 10008
A maintained, filterable compatibility matrix for the HTTP QUERY method (RFC 10008) across web frameworks (Express, Fastify, Hono, Rails, Spring, Django, ASP.NET Core), proxies/CDNs (nginx, Cloudflare, Akamai, Vercel, AWS ALB), and HTTP clients (curl, fetch, Postman, Insomnia, axios). No install, runs entirely in your browser.
Which JavaScript Temporal Type Should You Use?
Answer two quick questions about what you're modeling (a timestamp, a birthday, a recurring meeting) and get the exact Temporal type to use (Instant, ZonedDateTime, PlainDate, and more) with constructor code and the matching PostgreSQL column.
Try Python 3.14 t-Strings in the Browser
Paste a Python t-string template, fill in the values, and pick a renderer (HTML, SQL, structured log, LLM prompt, or raw). See the assembled output and how the Template splits into strings and interpolations. No Python 3.14 install needed.
Convert Next.js middleware.ts to proxy.ts Instantly
Paste your Next.js middleware.ts file and instantly get the converted proxy.ts version, with the export style updated and warnings for any Edge-runtime-specific patterns that need manual review.
Docker and Kubernetes Exit Code, Signal, and Pod Status Decoder
Type a Docker or Kubernetes exit code, signal, or Pod status and instantly get the plain-English meaning, the most common causes, and the exact diagnostic commands to confirm and fix it.
Convert pg, mysql2, ioredis Code to Bun.SQL and Bun.redis
Paste your existing pg, mysql2, or ioredis connection and query code, instantly get the equivalent Bun.SQL or Bun.redis syntax. No install, runs entirely in the browser.
Git Worktree Setup and Cleanup Command Generator
Answer a few questions about your setup, get the exact git worktree commands, a consistent naming convention, and a cleanup script. No install, no CLI tool to learn, runs entirely in the browser.
Which PostgreSQL ON CONFLICT Clause Should You Use?
Answer three quick questions about your use case, get the exact ON CONFLICT clause to use (DO NOTHING, DO UPDATE, or PostgreSQL 19's new DO SELECT) with working SQL and an explanation of why.
Convert C# OneOf Code to Native .NET 11 Union Types
Paste a C# method signature using OneOf<T0, T1, ...>, instantly get the equivalent native union declaration plus the converted switch-expression calling code, ready to paste into your codebase.
Compare Object Memory Layout: Today vs Project Valhalla
Define a Java class's fields, instantly see its memory layout under the current object model (header + fields + padding) versus what it could look like as a Project Valhalla value class (scalarized/flattened), with the byte savings calculated.
Verify Your npm Package Won't Leak Source Maps
Paste your package.json, .npmignore, and tsconfig.json to check whether your publish configuration will accidentally ship source maps. Get specific fixes and a CI automation snippet. Free, no uploads, runs in your browser.
Generate Subresource Integrity Hashes for Any CDN Script or Stylesheet
Paste any external script or stylesheet URL and instantly generate a valid Subresource Integrity (SRI) hash to pin that resource, preventing CDN supply chain attacks. Supports SHA-256, SHA-384, and SHA-512 with batch mode.
Convert next.config.js Redirects to Netlify, Vercel, or Nitro
Paste your next.config.js redirects, headers, or rewrites block and instantly get the equivalent config for Netlify (netlify.toml), Vercel (vercel.json), or Nitro (nitro.config.ts). No manual translation required.
Check Your MCP Server Config for Known Supply Chain Risks
Paste your mcp.json or claude_desktop_config.json and instantly check it against known MCP supply chain incidents and common risk patterns. No install, no server, 100% in your browser.
Compare Monthly LLM API Costs Across Claude, GPT-5, and Gemini
Enter your monthly API call volume and average prompt/response sizes to instantly compare costs across every major Claude, GPT-5, and Gemini model side by side, with context caching savings and a best-value recommendation.
TypeScript 7 Build Time and CI Savings Estimator
Enter your project's file count, lines of code, monorepo structure, and CPU cores to see your projected TypeScript 7 (tsgo) build time, speedup ratio, and monthly CI time and cost savings. Free, runs entirely in your browser.
Redis Memory Calculator and Instance Size Estimator
Estimate Redis memory usage from your key count, data type, and value sizes. Get a memory breakdown, encoding warnings, a recommended instance size, and a cloud pricing comparison. Free, runs entirely in your browser.
Check package.json for Outdated Deps, Deprecations, and CVEs
Paste your package.json and instantly see which dependencies are outdated, deprecated, or have known CVEs, plus last publish date and weekly downloads. No install, no login, runs entirely in your browser.
Generate and Understand tsconfig.json for Any TypeScript Project
Pick a framework preset (Next.js, Vite, Node.js, library, Deno), toggle compiler options with plain-English explanations for each one, and get a correct tsconfig.json instantly. Free, no setup, runs in your browser.
Convert tailwind.config.js to Tailwind v4 @theme CSS Instantly
Paste your Tailwind v3 tailwind.config.js theme.extend block and get the equivalent Tailwind v4 @theme CSS instantly, with a per-section conversion coverage report. Free, no setup, runs in your browser.
Visual git log --pretty=format Builder with Live Preview
Click placeholders to build a git log --pretty=format: string, see a live preview with realistic sample commits, and copy the finished command or .gitconfig alias. Free, no account, runs in your browser.
Browser-Based MCP Tool Tester & Schema Viewer
Paste an MCP server's tools/list JSON and instantly see every tool, its input schema, and required vs. optional fields in a clean card layout. No installs, no login, no server needed.
Estimate Your GitHub Copilot Token Billing Cost
Enter your Copilot plan, daily workflow habits, and model preferences to instantly see your estimated monthly AI Credit spend, whether you'll hit overages, and whether switching to Cursor, Claude Code, or Windsurf makes financial sense.
npm Semver Range Explainer
Paste your package.json or type any npm version range and instantly understand which versions are allowed, what ^ and ~ mean, and whether your constraints are too loose. Free, no server, runs in your browser.
Compare .env Files, Find Missing Keys Instantly
Paste two .env files and instantly see what keys are missing, empty, or different. Key-level diff that understands .env semantics — not a line diff. No uploads, no server, runs entirely in your browser.
Instant, Ad-Free, Three Encoding Modes
Encode or decode URLs instantly in your browser. Three modes: Component (encodeURIComponent), Full URL (encodeURI), and Form data. Auto-detects encoded input, no ads, no trackers, nothing sent to any server.
Instant, Ad-Free, Privacy-First
Encode or decode Base64 instantly in your browser. No ads, no trackers, nothing sent to any server. Supports Unicode, URL-safe mode for JWT tokens, swap, copy, and auto-detection of Base64 input.
Instant Score, Token Breakdown, Selector Comparison
Paste any CSS selector and instantly see its specificity score (a, b, c), a token-by-token breakdown of every contributing part, and a plain-English explanation. Compare two selectors to find out which wins.
Visual Builder, Plain-English Explainer, Next Run Times
Type or build a cron expression and instantly see what it means in plain English, the field breakdown, and the next 5 scheduled run times in your local timezone. No account, no ads.
Promise.all vs Sequential await — animated
Configure async tasks, pick a pattern — sequential, Promise.all, or Promise.allSettled — and watch an animated Gantt chart show exactly when each task runs. Add failures to see how each pattern responds.
Interactive Selector Tester
Pick a preloaded HTML scene — forms, cards, nav, todo list, and more — type a CSS :has() selector, and see matched elements highlight live in your browser. No CodePen, no setup.
VS Code Extension Security Checker
Paste your VS Code extension list and get a risk report in seconds. Checks publisher verification status, last update date, and install count for every extension at once — no CLI, no account.
Conventional Commits Validator
Validate Git commit messages against the Conventional Commits spec in real time. Paste a message and get plain-language feedback on exactly what's wrong — no Commitlint setup required.