Free tools for builders
Practical blockchain and developer utilities, free, fast, and private. No sign-up required.
Blockchain tools
6Smart Contract Vulnerability Scanner
Paste your Solidity code and get an instant heuristic scan for the OWASP Smart Contract Top 10 vulnerabilities.
Smart Contract Audit Cost Estimator
Estimate what a professional smart contract audit will cost based on your codebase size and complexity.
Gwei / ETH / USD Gas Fee Converter
Convert between Gwei, ETH and USD to understand transaction and deployment gas costs.
Keccak-256 Hash Generator
Generate the Keccak-256 (Ethereum SHA-3) hash of any string or function signature.
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates, handy for block times and vesting schedules.
Wallet Address Validator
Check whether an Ethereum address is well-formed and EIP-55 checksum valid.
SEO tools
4Meta Tag Generator
Generate SEO title, description, Open Graph and Twitter tags with a live Google search-result preview.
Schema Markup (JSON-LD) Generator
Generate FAQ, Article and Breadcrumb JSON-LD structured data to paste into your pages.
Robots.txt Generator
Build a valid robots.txt with crawl rules and sitemap directives.
XML Sitemap Generator
Crawl a website and generate a downloadable XML sitemap for search engines.