Dev

50 tools

Regular Expression Cheat Sheet

A quick reference of commonly used regular expressions covering 18 everyday cases such as email, phone number, URL, IP, ID card number and date, each with an explanation, plus keyword search and one-click copy.

LLM Temperature & Top-P Sampling Visualizer

An interactive visualization using 12 built-in mock token probabilities that shows how temperature and top-p (nucleus sampling) reshape an LLM's output distribution - a local simulation, not a real model call.

Text Embedding Similarity Playground

Enter one query sentence and up to 10 candidate sentences to compute and rank similarity scores using three lexical-overlap methods - Jaccard, cosine (bag-of-words), and simplified TF-IDF - a demo of the concept, not a real embedding model.

LangChain Prompt Template Builder

Visually build a LangChain ChatPromptTemplate with System/Human/AI messages, variable placeholders and few-shot examples, and generate copy-ready Python or JavaScript code.

Model Evaluation Metrics Explainer

Quick reference for ML and LLM evaluation metrics - BLEU, ROUGE, F1, pass@k, BERTScore and more - with formulas, ranges and use cases, plus an interactive confusion matrix calculator.

Vector Dimension Comparison

Compare vector dimensions, context length, MTEB scores and prices of mainstream embedding models, with filtering and sorting, plus storage estimation for millions of text chunks.

MCP Server Boilerplate Generator

Generate ready-to-use TypeScript or Python MCP server skeleton code from your server info and tool definitions, right in the browser.

WebAssembly Module Size Estimator

Estimate the min/typical/max size range of a WebAssembly module based on source language, compile target, optimization level, and selected feature modules — a heuristic estimate, not a real file analysis.

WebRTC STUN/TURN Config Builder

Visually add STUN/TURN servers and ICE options, then generate ready-to-use RTCConfiguration JavaScript code and a JSON config file.

GraphQL Subscription Builder

Visually define a GraphQL subscription's name, arguments, and return fields, and generate the subscription query plus WebSocket connection sample code — no real connection is made in the browser.

Edge Function Cold Start Estimator

Estimate cold-start/warm-start latency and TTFB for edge functions based on platform, bundle size, and dependency count, with a cross-platform comparison and optimization tips — based on typical public benchmark values.

WebGPU Compute Shader Demo

Browse full WGSL shader source and WebGPU JavaScript call code for matrix addition, dot product, and reduction sum, with a JavaScript-computed CPU reference result. Detects real WebGPU browser support but does not actually dispatch the shaders to a GPU.

HTMX Request Builder

Visually pick an HTMX request method, trigger event, target, and swap strategy, then generate ready-to-use HTML element markup with a live preview and an attribute reference table.

WASM Binary Format Parser

Paste WASM binary as hex or Base64, or upload a .wasm file, and get a real, local, in-browser parse of the module header, section list, import/export tables, and type signatures — instruction streams inside function bodies are not decoded.

Pyodide Script Runner Generator

Write Python code, pick the scientific packages you need, and generate a self-contained HTML file with Pyodide embedded. Opening that generated file runs your Python for real via Pyodide — this builder page itself does not execute Python.

gRPC Request Builder

Paste .proto content or manually enter a Service/RPC definition to generate a grpcurl command plus JavaScript, Python, and Go gRPC client call code.

LLM Token Counter

Estimate how many tokens a piece of text will use with LLMs such as GPT and Claude, and see how much of a 16K, 32K, 128K or 200K context window it fills. Everything is calculated locally in your browser.

LLM API Cost Calculator

Enter input and output token counts plus a daily call volume to estimate per-call and monthly API spend against a built-in reference price list covering GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 and more. Prices are for reference only - always check the vendor's current pricing.

Prompt Template Variable Editor

Paste a prompt template containing {{variable}} placeholders and the tool extracts every variable, builds a form for them, previews the filled-in result live and copies the final prompt in one click.

JSON Schema Validator

Put a JSON Schema on the left and the JSON data to check on the right, and get live validation with the exact failing field path and reason. Includes a one-click OpenAI function calling example. It implements a common subset of keywords, not the full JSON Schema spec.

RAG Text Chunking Calculator

Paste a long document, set chunk size and overlap, and see it split locally by estimated token count, with the character count, estimated tokens and a content preview for every chunk - handy for tuning RAG chunking strategy.

Vector Similarity Calculator

Compute cosine similarity, Euclidean distance and dot product between two vectors, or rank a batch of candidate vectors against a query vector to simulate retrieval - useful for debugging embedding and RAG results.

File Backup Rotation Schedule

Generate a Grandfather-Father-Son backup rotation schedule with configurable daily, weekly, monthly and yearly retention. See backup counts, estimate storage needs and get media rotation advice, plus a 3-2-1 strategy reference.

OpenAPI and Swagger Spec Validator

Check the basic structure of an OpenAPI 3.x document (openapi, info, paths), browse the endpoints grouped by path, and catch common issues such as missing responses or duplicate operationIds. JSON input only - YAML is not parsed.

GraphQL Query Formatter

Format GraphQL query, mutation and subscription text with consistent indentation, or minify it to a single line. Syntax checking is limited to bracket-stack matching - this is not a full AST parser.

.env File Parser

Parse a .env file online, flag common problems such as duplicate keys, missing equals signs and unquoted values, mask secret-looking values, and export the result as a JSON object or shell export statements.

Semantic Version Calculator

An online semver calculator for bumping versions (major/minor/patch/prerelease), comparing two versions, and testing whether a version satisfies a ^ or ~ npm range, following the semver.org specification.

.gitignore Generator

Tick templates for Node.js, Python, Java, Go, Rust, macOS, Windows, Linux, VSCode, IntelliJ IDEA and Docker, and the tool merges and deduplicates them into a ready-to-download .gitignore file.

README Badge Generator

Generate shields.io badge Markdown or HTML online, covering custom text badges, license badges, version badges (including live npm lookups) and build status badges, with a live preview.

OpenAI Fine-tuning JSONL Validator

Validate JSONL datasets in the OpenAI fine-tuning chat format line by line, checking the messages structure, role validity and user/assistant completeness, and reporting sample counts with an estimated token total.

SQL Explain Plan Analyzer

Paste MySQL or PostgreSQL EXPLAIN JSON output and get a clean, tree-style execution plan with warnings for table scans, high-cost nodes and actionable tuning tips.

Regex Performance Tester

Run a regex for real in your browser with timing, match counts, and a static analysis that flags catastrophic backtracking patterns before they freeze your production code.

Prompt Injection Escaper

Escape and wrap untrusted text before embedding it in an LLM prompt, and flag common injection keywords, to reduce prompt injection risk. This is a mitigation, not a complete defense.

YAML Anchors and Aliases Explainer

Parse anchors (&name) and aliases (*name) in YAML, count definitions and references, expand everything into complete YAML, and compare original, expanded and side-by-side views.

Cron Expression Humanizer

Translate 5 or 6 field cron expressions into plain-language descriptions with next run times. Supports L, W, # and @daily presets, plus a visual builder that generates cron from options.

UUIDv7 Generator

Generate RFC 9562 compliant UUIDv7 values, decode the timestamp encoded inside any UUIDv7, and generate batches to compare the sortability of v7 against v4 side by side.

JWT Claim Visualizer

Decode a JWT's header, payload and signature locally, group claims into registered, public and private, and see expiry status, remaining validity and the iat/nbf/exp timeline at a glance.

Markdown Front Matter Parser

Parse the front matter at the top of Markdown files used by Hugo, Jekyll and Next.js, separating fields from body text and merging them back into a complete document after form editing. Uses a simplified YAML parser, not a full specification implementation.

Code Review Checklist Generator

Generate a code review checklist from programming language, project type and review dimensions. Items are rated critical, major or minor with explanations, and can be ticked off with counts.

API Doc Previewer

Fill in endpoints, parameters and response examples through forms, and instantly generate a Markdown API doc, an OpenAPI 3.0 YAML spec and a rendered preview. No coding needed.

JSON Query Builder

Build JSONPath queries visually with filter, slice and recursive search operators, get jq and other language equivalents, and preview matches against pasted JSON data.

SSL Certificate Expiry Check Script Generator

Generates OpenSSL commands, Bash batch scripts, and Python scripts for checking SSL certificate expiry from a domain list — the tool itself makes no network requests; you run the output locally.

Domain SSL/TLS Security Configuration Checklist

A 20-item manual SSL/TLS security self-audit checklist across certificates, protocols, cipher suites, HTTP security headers, and DNS security — each item ships with a suggested command; generates a graded report, but never scans your domain automatically.

Common Regex Patterns

A searchable cheat sheet of regular expressions for phone numbers, email addresses, ID numbers, dates, IP addresses and more, with a built-in tester.

CDN Cache Purge Command Generator

Pick a CDN provider (Alibaba Cloud, Tencent Cloud, Cloudflare, AWS, Azure, or generic) and operation type, enter a URL list, and generate curl commands plus Python/Node.js/CLI code in one click — all credentials are placeholders and no request is ever actually sent.

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