Estimate password strength with Dropbox's zxcvbn: score 0-4, estimated guesses and crack time for online and offline attacks, weak patterns found (dictionary, dates, sequences...) and tips. Evaluated in memory, never stored or logged.

Nostr profile by npub, hex key or NIP-05 identifier (name@domain): name, bio, picture, website, NIP-05, Lightning address and latest public notes, queried from several public relays.

Pendle markets (fixed yield in DeFi): asset, maturity, days left, implied fixed APY (buying PT), LP APY and liquidity, on Ethereum, Arbitrum, Base, BNB and other chains.

Current owner of an ERC-721 NFT by token_id (ownerOf), with collection name and tokenURI. Works on Base, Ethereum, Arbitrum, Optimism, Polygon, BNB Chain, Avalanche, Gnosis, Linea, Scroll, Sonic and Unichain.

NEAR account (name.near or 64-hex implicit): available and staked NEAR, storage used, whether it has a contract deployed and USD value.

Write a number or money amount in words, in Spanish or English (EUR, USD, GBP, MXN), with correct Spanish apocope (veintiún, un millón de euros). For invoices, cheques and contracts.

Images on a page with URL, alt text, declared size, lazy loading and format, counting images without alt text and flagging missing modern formats. For accessibility and SEO audits.

Kaspa: balance of an address (kaspa:...) with transaction count and USD value; without an address, network status (blocks, difficulty, hashrate, circulating and max supply).

Find a company's LEI (Legal Entity Identifier) by name, or the record of a LEI: legal name, country, legal form, address, entity and registration status, renewal date, direct parent and company register number.

Pricing calculator: from any two of cost, price, margin or markup it computes the rest, profit per unit and total, and the price with VAT. Avoids the classic margin vs markup confusion.

Compare two lists (emails, IDs, wallets, SKUs...): items in both, only in A, only in B, duplicates within each and union, with counts. Up to 100,000 items per list.

Count the tokens of a text with OpenAI tokenizers (o200k for GPT-4o/4.1/5, cl100k for GPT-4/3.5) plus estimates for Claude, Llama and Gemini, with characters per token. Budget LLM calls and split contexts.

IPv4/IPv6 subnet calculator: network, mask, wildcard, broadcast, first/last host, usable hosts, address type (private, public, loopback...) and whether a given IP belongs to the subnet.

Validate JSON (with line and column of the error), pretty-print or minify it, describe its structure (depth, keys, value types) and extract a value by path such as data.items[0].price.

Read a website's /llms.txt (the standard that tells LLMs what a site is about) as structured data: title, summary, sections with links and descriptions, and whether llms-full.txt exists.

Validate a securities ISIN (ISO 6166): format, check digit, issuing country and embedded CUSIP (US/CA, with its own check) or SEDOL (GB/IE). Computed locally; nothing stored.

Public information about an IP address: network prefix, autonomous system (ASN) and holder, registration country, regional registry and abuse contact, or whether it is private/reserved. RIPEstat data.

Moon phase on a date: name, illuminated percentage, lunar age and the next new and full moon dates. Local astronomical calculation.

Dominant colors of an image (URL or base64) with their share, in HEX and RGB, plus the average color and light/dark tone. For brand palettes, themes or tagging images by color.

totalSupply of an ERC-20 token or ERC-721 collection with name, symbol and decimals. Works on Base, Ethereum, Arbitrum, Optimism, Polygon, BNB Chain, Avalanche, Gnosis, Linea, Scroll, Sonic and Unichain.