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Showing the 18,689 endpoints that answered our last unpaid knock, most recently knocked first. The catalogue holds 76,774 listings in all: 18,116 charge, 630 answered without asking, 8,803 did not reach a working endpoint, and 49,225 we have never knocked on. Type something above to search all of them.
Parse a scientific name into genus, species epithet, subspecies or variety, authorship and year, and check capitalisation.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Hold exposure constant: change one setting (aperture, shutter or ISO) and get the other two compensations, in stops.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Convert fuel economy between US mpg, UK mpg, km per litre and litres per 100 km, with optional trip fuel and cost.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
How many identical boxes fit inside a larger box or crate: best of six orientations in a simple grid, with utilization.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Select among conflicting results using explicit policy
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Standard deviation of sampled surface elevations. The coordinate is validated against the Natural Earth boundary for Estonia; results outside it are rejected before payment.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Eigenvalues and eigenvectors of a 2x2 matrix (closed form) or a symmetric matrix up to 10x10 (Jacobi).
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Board feet for lumber from thickness, width, length and quantity (nominal sizes), with total cost at a price per board foot.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Mean SoilGrids clay fraction for the 0-5 cm layer. The coordinate is validated against the Natural Earth boundary for Cyprus; results outside it are rejected before payment.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Wavelength and half-wave dipole, quarter-wave vertical and full-wave loop lengths for a frequency, with velocity factor.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
List current OSI-approved SPDX licenses, optionally only FSF-libre ones or those starting with a prefix.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Years to double money at a growth rate (exact and by the rule of 72), and how long inflation takes to halve buying power.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Search the SPDX license list by name or id fragment, such as gpl or creative commons, with OSI and deprecated flags.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Verify a citation: does the DOI exist, does its real title match the claimed title, and has it been retracted?
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Baker's percentages and hydration from a gram formula, counting sourdough starter, with scaling to a flour or dough weight.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
True airspeed, Mach and equivalent airspeed from calibrated airspeed, pressure altitude and outside air temperature.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Concrete for a slab: cubic yards with waste, ready-mix order size and the number of 40, 60 or 80 lb bags of mix.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Validate an SPDX license expression (AND, OR, WITH, +): syntax, known ids, known exceptions and deprecated identifiers.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Count business days between two dates, skipping weekends and your holiday list, NETWORKDAYS style.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Wallet Portfolio: Get a complete wallet portfolio for an Ethereum address: native ETH balance, ERC-20 balances, NFT holdings, recent transfers. Pay per call in USDC on Base via x402 — POST https://x402.freeq.one/tools/wallet_portfolio.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Correlation, beta, R-squared and alpha of one return or price series against another you supply. Not advice.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Compound annual growth rate from start and end values over years, or dates, or periods. Arithmetic on your numbers, not advice.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Convert an ISO 3166-1 country code between alpha-2, alpha-3 and numeric; also name, currency, ccTLD, calling code.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Journal profile by name: output, citations, h-index, open-access status, DOAJ listing, article fee and quality flags.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
NYSE market holidays and 1 PM early closes for a year, with the weekday of each, from the exchange's published rules.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Day length, sunrise, sunset (UTC) and solar noon for a latitude, longitude and date, including polar day and night.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Returns a JSON object with the caller IP address as a string
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Use when an agent needs the top x402 services tagged 'inflation'. Returns Highest-demand x402 services tagged 'inflation': ranked by 30-day unique paying wallets, with calls, price, network and calls-per-payer for each. 44 providers and 70 paying wallets measured in this tag.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
List a website's URLs from its sitemaps. Reads robots.txt and sitemap indexes (gzip supported) and returns up to 2000 URLs with lastmod dates.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Planetary Kp index over the last 3-168 hours: latest, peak, trend and the NOAA G storm level it maps to.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Solve x = a1 (mod m1), x = a2 (mod m2), ... with the Chinese remainder theorem, coprime or not.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
A sunlit grassy meadow bordered by tall evergreen conifers in a mountain forest. Green vegetation and yellow wildflowers fill the...
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Country demographics: population, 10-year population growth, life expectancy and internet use, with an ageing/growing verdict.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Solve ax^2 + bx + c = 0: real or complex roots, discriminant, vertex, axis of symmetry and factored form.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Vet a directory, publication or sponsor pitch before paying: domain age (RDAP), Tranco rank, Google News presence, outbound-link dilution, badge and pay-to-play signals, score 0-100 with red flags
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Counterparty Report: a company, its ownership parents and a sanctions screen of the whole group, with one verdict — Genesis402 / UnyKorn Operator Network
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
MRR, ARR, customer lifetime, annualised churn and LTV from customers, ARPU and monthly churn, with optional CAC payback.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Split a tax-inclusive price into net and tax, or add tax to a net price, for a sales tax or VAT rate you supply.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Deterministically gate caller-supplied field contracts before ingestion, migration, CI deployment, or machine-to-machine handoff; returns stable incompatibility codes and remediation actions without fetching data or validating API behavior.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Contract IP Review - Scan a freelancer contract or clause and highlight unfair intellectual-property provisions, explain legal risks, and suggest safer wording.
The price is the seller’s own listing. it answered us without asking for payment, once, on the day we knocked, on 2026-10-21.
Generate a CSS clamp() that scales a size linearly between a min and max viewport width, in rem, with the exact slope.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Prediction market search — find Polymarket events by free text and get each event's status, dates, volume, liquidity, topic tags and its markets with current YES prices. Use to locate a market on an election, Fed decision, crypto price, geopolitical or AI question before pulling odds, history or the order book.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Chance of a run: r successes in a row (or r identical outcomes) somewhere in n independent trials, like coin flips.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Estimate the USD cost of a transaction (transfer, ERC20 transfer, approve, swap, NFT mint) on Base/Ethereum/Arbitrum/Optimism/Polygon from live gas price and native token price - lets agents decide whether an action is worth the fee before sending. gas cost, transaction cost, tx fee usd, how much gas, operation cost, fee estimate Accepts payment on Base or Solana — either network works.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Scrape any URL and get clean markdown content — ideal for extracting readable text from web pages
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
A foggy outdoor scene shows a white vehicle roof in the foreground with stone buildings and desert vegetation shrouded in mist.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Levenshtein and Damerau-Levenshtein edit distance (restricted and unrestricted) between two texts, with a 0 to 1 similarity.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Cubic yards and approximate tons of gravel, sand, topsoil, mulch or compost to cover an area at a given depth.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
Koppen-Geiger climate class (such as Cfa or BSk) for a location, computed from its monthly temperature and rainfall normals.
The price is the seller’s own listing. it demanded payment when we knocked, on 2026-10-21.
The description and the price are the SELLER’S, copied from their listing and not checked by us. The badge is OURS and is one unpaid handshake: “answered unpaid” means it answered us once without asking for payment, which is not a standing offer, and an unpriced listing is unpriced rather than free.
Knocking goes to the knock page, which reads the terms live before anything is signed. A listing can be out of date in both directions, which is the reason to knock rather than to read a row.