Deduplicate array. Remove duplicate values from a JSON array - primitives or objects (deep equality) - preserving order.

Deduplicate lines. Remove duplicate lines from text while preserving first-seen order; optional case-insensitive and trim modes.

Depreciation calculator. Asset depreciation schedules: straight-line and declining-balance methods with year-by-year book values.

Dice roller (RPG notation). Roll dice in standard notation like 3d6+2 or 2d20 - individual rolls, total, min/max - games and simulations.

Stacked discount calculator. Apply a chain of successive discounts and/or a tax to a price (e.g. 20% then 10% then +18% VAT) - the true final price.

DMS ↔ decimal degrees. Convert coordinates between degrees-minutes-seconds (31°31'13"N) and decimal degrees (31.5204), both directions.

Humanize duration. Turn a duration in seconds or milliseconds into human-readable text like '2 days 3 hours 10 minutes'.

Payment URI parser (EIP-681). Parse an ethereum: payment URI into target address, chain ID, value and function parameters - wallet QR payment links.

ENS namehash. Compute the ENS namehash (EIP-137) of a .eth or any ENS name - resolver lookups and on-chain ENS work.

Ethereum address validator. Validate an Ethereum/EVM address: format check plus EIP-55 checksum verification; returns the correct checksummed form.

EIP-55 checksum address. Convert any Ethereum address to its EIP-55 mixed-case checksummed form.

Raw transaction decoder. Decode a raw signed Ethereum transaction (legacy or EIP-1559 0x02) into nonce, gas, to, value, data and signature parts, plus its hash.

Ethereum unit converter. Convert between wei, gwei and ETH with exact BigInt math - gas math, balances, transaction values.

EVM function selector. Compute the 4-byte function selector and full event topic hash from a Solidity signature like transfer(address,uint256).

Structured extraction (CSS selectors). Scrape structured data from any public page: give a URL (or raw HTML) plus named CSS selectors, get clean JSON back. Supports text, attributes (href, src, ...), innerHTML, and all-matches arrays. The fast lane for agents that need facts off a page, not prose.

Extract email addresses. Find and extract all email addresses from any block of text, deduplicated.

Extract fields (AI). Pull structured JSON from messy text given a list of fields. Powered by openai/gpt-4o-mini. Max 700 output tokens.

Extract URLs. Find and extract all http/https URLs from any block of text, deduplicated.

Feed conversion ratio (FCR). Compute FCR (feed consumed / weight gained) and cost per kg of gain for poultry, cattle, fish - the core livestock efficiency metric.

FIFO inventory costing. Cost of goods sold and remaining inventory value using FIFO from purchase lots and a sale quantity - accounting-grade.

Find and replace. Replace all occurrences of a literal search string in text, with optional case-insensitive matching. Returns replacement count.

Query string to JSON. Parse a URL query string into a JSON object; repeated keys become arrays.

Fuel economy converter. Convert between MPG (US and imperial), L/100km and km/L - the inverse-scale conversion everyone gets wrong.

Gas cost calculator. Compute transaction cost in ETH (and USD if you give a price) from gas used and gas price in gwei - fee estimation for EVM chains.

GCD and LCM. Greatest common divisor and least common multiple of a list of integers, exact BigInt math.

Grain moisture shrink. Weight loss when drying grain from one moisture percentage to another, with shrink percent and dry weight - grain trading and storage.

Distance between coordinates. Great-circle (haversine) distance between two lat/lon points in kilometers, miles and nautical miles.

HD derivation path parser. Parse and validate a BIP-32/44 derivation path like m/44'/60'/0'/0/0 - purpose, coin type (BTC/ETH/SOL...), account, change, index.

Hex decode. Convert a hexadecimal string back to UTF-8 text.

Hex encode. Convert text or UTF-8 data to a hexadecimal string.

Endian swapper. Reverse the byte order of a hex value - Bitcoin block hashes and little-endian protocol fields.

Hex to HSL. Convert a hex color to HSL (hue, saturation, lightness) - the color space for programmatic adjustment.

Hex to RGB. Convert a hex color (#FFB000) to RGB and HSL values.

Hijri ↔ Gregorian date converter. Convert dates between the Islamic Hijri calendar and Gregorian, both directions - tabular algorithm, ±1 day of official moon sightings.

HMAC signature. Compute an HMAC (SHA-256 or SHA-512) of a message with a secret key - webhook signing and verification.

HSL to hex. Convert HSL values back to a hex color string.

HTML escape. Escape text for safe embedding in HTML: & < > " ' become entities. XSS-safe output encoding.

Strip HTML tags. Remove all HTML tags from markup and decode entities, leaving readable plain text with preserved line breaks.

HTML unescape. Convert common HTML entities (named and numeric) back to plain characters.

HTTP status code lookup. Explain any HTTP status code: name, class, and what it means - including 402 Payment Required, the x402 heartbeat.

IDN / punycode domain converter. Convert internationalized domain names between Unicode and punycode (xn--) forms, both directions - non-Latin domains.

Impermanent loss calculator. IL for a 50/50 liquidity position from the price-change ratio - what LPs lose versus holding.

Invoice line-item totalizer. Total an invoice from line items (qty × unit price), with per-line and invoice-level discount and tax - returns the full computed invoice.

IP address converter. Convert IPv4 addresses between dotted, integer, hex and binary forms, both directions.

IPFS CID validator + converter. Validate IPFS content IDs and convert CIDv0 (Qm...) to CIDv1 (bafy...) - pinning, gateways, NFT metadata.

Internal rate of return (IRR). Find the internal rate of return of a cash-flow series - the discount rate where NPV is zero. Investment comparison standard.

ISO date to Unix timestamp. Convert an ISO 8601 or common date string to Unix epoch seconds and milliseconds.

Flatten nested JSON. Flatten a nested JSON object into single-level dot-notation keys: {a:{b:1}} becomes {'a.b':1}. Great for CSV export and diffing.

List all JSON paths. List every dot-notation path in a JSON object with its type and depth - schema discovery for unknown payloads.

JSON lint / validity check. Check whether a string is valid JSON; returns the parse error position and message if broken.