▸ Free tools
Tools I built because I needed them.
Free, no-signup engineering tools for LLM math, encoding, JSON, infra, and Shopify. They run in your browser, except the agent readiness checker, which fetches a public URL and stores nothing.
▸ 34 tools · free · no signup
▸ 33 run in your browser
▸ Agent readiness fetches the URL you enter and stores nothing
AI & LLM
Budget a prompt before it bankrupts you: token math, context windows, chunking, and API spend.
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LLM Cost Calculator
Estimate API spend across Claude, GPT and Gemini, with real prompt-cache read and write prices. See the monthly bill before you ship.
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Token Counter
Paste any text for an exact GPT token count, plus Claude and Gemini estimates, characters, words and per-call cost. All in your browser.
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Context Window Checker
Will the prompt fit? Paste it and see tokens used, headroom left, and what's still free for the answer across Claude, GPT and Gemini windows.
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RAG Chunk Splitter
Split text into retrieval chunks — fixed, sentence, paragraph, or markdown-heading aware — and see every chunk's token count and overlap seam.
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pgvector Size Calculator
Rows and dimensions in, table size, HNSW or IVFFlat index size, RAM and maintenance_work_mem out. vector, halfvec and bit, with the formulas shown.
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Prompt Caching Calculator
Compare the LLM bill with and without prompt caching. Prefix tokens, hit rate, write premium and read discount in, savings and break even hit rate out.
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MCP Config Generator
Build the MCP server config for Claude Desktop, Claude Code, Cursor or VS Code, stdio or remote HTTP. Paste a config to find what is wrong with it.
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llms.txt Generator & Validator
Fill in a short form and get an llms.txt file in the llmstxt.org format, or paste one to check it line by line. Starts from your sitemap if you like.
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Agent Readiness Checker
Paste a URL and a site type. See if agents can find, read, and respect the site, with copy-paste fixes for the gaps that apply.
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Encoding & secrets
Encode, decode, hash, and generate. Every one of these runs client-side — nothing is transmitted.
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JWT Decoder
Paste a JWT and read its header and payload — claims, algorithm, and expiry decoded in your browser. Decode-only; nothing is sent anywhere.
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Laravel Encrypt / Decrypt
Decrypt or encrypt Laravel Crypt payloads and cookies with your APP_KEY. AES-CBC with MAC check and AES-GCM, all in your browser.
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Base64 Encoder / Decoder
Encode and decode base64 without the UTF-8 bugs — emoji and accents round-trip correctly. base64url and file-to-data-URI included.
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SHA Hash Generator
SHA-1, SHA-256, SHA-384 and SHA-512 for text or a file, plus HMAC with your own key. Hex or base64, Web Crypto, in your browser. No MD5, on purpose.
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Secret & API Key Generator
Keys, hex secrets, passphrases and Laravel APP_KEY values from crypto.getRandomValues, never Math.random. Unbiased sampling, entropy readout, nothing logged.
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UUID Generator
Generate v4 or time-ordered v7 UUIDs in bulk, and paste any UUID to read its version and timestamp. Crypto-random, instant, offline.
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Data & APIs
JSON, URLs, and schemas. The tools you reach for mid-debug with a payload in your clipboard.
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URL Parser & Encoder
Break a URL into every part, edit query params and watch it rebuild. Plus the four encode/decode functions people keep mixing up.
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JSON Formatter & Validator
Format, minify, sort keys — and when it breaks, get the line, the column, and a caret under the exact character, not just “Unexpected token”.
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PHP Unserialize & Laravel Job Decoder
Read PHP serialized data as a tree and JSON without running any code. Paste a failed_jobs payload to see the job, its queue and the models it was given.
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JSON to TypeScript & Zod
Paste a JSON sample, get typed interfaces plus a Zod v4 schema — unions merged, optionals inferred, dates and emails detected.
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Infrastructure
Cron, timestamps, permissions, bandwidth, latency, capacity. The arithmetic nobody wants to redo by hand.
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Cron Explainer
Decode a cron expression into plain English, see the next five run times and get the Laravel scheduler line. Built it for my own schedulers.
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Epoch Converter
Unix timestamp in, human date out — UTC, local, ISO 8601, relative. Auto-detects seconds vs milliseconds, which is the bug you actually had.
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Chmod Calculator
Tick boxes or type 755 — both stay in sync. Setuid, setgid and sticky included, with the S/T rendering most calculators get wrong.
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Transfer Time Calculator
How long to move X at Y bandwidth. Bits vs bytes, GB vs GiB, and the protocol overhead that line-rate maths always forgets.
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Latency Percentile Calculator
Paste response times, get p50 through p99.9 with a histogram — and a warning when your sample is too small for the percentile you asked for.
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Server Capacity Calculator
Little's Law sizing: requests/sec × latency → workers you actually need. Includes the Erlang C queue math for what happens near full utilization.
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Postgres Connection Pool Calculator
Count the Postgres connections your PHP-FPM or Octane servers, Horizon workers and scheduler can open, compare them with max_connections and get PgBouncer settings.
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Self-Hosting Cost Calculator
Coolify on a VPS versus Render, Railway or Heroku for the same apps, workers, Postgres and Redis. Every price is editable, and your ops hours count too.
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Shopify
Built while shipping Shopify apps — webhook verification and the ID formats that keep changing.
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Shopify Webhook HMAC Verifier
Check a webhook, app proxy or OAuth signature against your client secret, constant-time, in the browser. When it fails, it tells you the likely cause.
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Shopify GID Decoder
gid://shopify/Product/123 in, resource type and legacy numeric ID out — or the reverse. Handles the base64-encoded IDs older APIs still return.
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Shopify Rate Limit Planner
GraphQL Admin, REST or Storefront, by plan: throughput, time to sync N records, batch size and concurrency. Paste a response to use your real costs.
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Shopify API Version Calendar
Every Shopify API version with its release date, end of support and fall-forward date, computed from Shopify's quarterly rule. Check how many months your version has left.
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Reference
Lookup tables I got tired of searching for. Status codes, headers, ports — filterable, no ads.
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HTTP Status Codes
Every 1xx–5xx code with what it means and when to actually use it — including 307 vs 302, 401 vs 403, and the non-standard ones. Filterable.
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HTTP Headers Cheat Sheet
Request and response headers that matter in production — caching, CORS, security, forwarding — each with a real example value. Filterable.
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Common Ports
TCP and UDP ports for web, databases, caches, Docker, Kubernetes and dev servers — each with a practical note on what listens there and why.
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