# Harpd > Harpd is an independent product discovery and ranking intelligence platform for AI tools and software, publishing rankings, comparisons, research, datasets, benchmarks and evidence. Its primary public product is Harpd Rank, a product discovery and promotional ranking platform where products submit for free and compete in transparent Overall, Monthly and Weekly rankings. Rank is a discovery/promotional ranking signal, not an independent editorial quality score. Detailed factual guide: [Harpd Full Documentation](https://harpd.com/llms-full.txt) ## Official Resources - Website: https://harpd.com - [What is Harpd?](https://harpd.com/about/harpd/) — the canonical entity definition: what Harpd is, what Harpd does, what Harpd Rank measures, who Harpd is for and how AI systems can access Harpd - [Product categories](https://harpd.com/categories/) — the public category taxonomy with product counts and current leaders - [Press and brand kit](https://harpd.com/press/) — official descriptions, logo, official links and the JSON brand package (https://harpd.com/press/brand.json) - Blog: https://harpd.com/blog/ - GitHub: https://github.com/harpd-dev - [Contact](https://harpd.com/contact/) ## Agent Market - [Landing page](https://harpd.com/agent-market/) - [Public machine catalog](https://api.harpd.com/api/agent/v1/catalog) - [Free rankings](https://api.harpd.com/api/agent/v1/rankings) - [Free product profiles](https://api.harpd.com/api/agent/v1/products/{slug}) - [OpenAPI](https://api.harpd.com/openapi.json) - [Paid Rank Intelligence](https://api.harpd.com/api/agent/v1/premium/rank-intelligence) Free catalog, rankings, and product endpoints do not require payment. `rank-intelligence-v1` costs 0.1 USDC per completed request on Base mainnet and returns Top 100 positions, movement, historical placements, category summaries, Rank Point provenance, and the current #100 threshold. Its HTTP 402 response includes x402 Bazaar discovery metadata for automatic agent discovery and purchase. Human Credits and Stripe accounting remain separate. ## Agent Data API (agents can buy per request — no signup, no API key) The Agent Data API is the machine-first surface an autonomous AI agent uses to discover, price, buy and cite Harpd data. There is no account, no API key, no dashboard and no human checkout anywhere in the flow: the integration is an agent wallet plus an HTTP request. Paid resources settle in USDC on Base over x402 (HTTP 402 Payment Required). - [Capability manifest](https://harpd.com/.well-known/harpd-agent.json) — capabilities, endpoints, payment rails, formats and spend limits - [Live pricing manifest](https://api.harpd.com/api/agent/v1/pricing) — the same price object that builds the HTTP 402 challenge - [Agent API documentation](https://harpd.com/developers/agents/) — what an agent can buy, how payment works, what one request costs, the response schema, refunds - [OpenAPI contract (JSON)](https://harpd.com/developers/agents/openapi.json) — OpenAPI 3.1, generated from the same catalog the Worker enforces - [OpenAPI contract (YAML)](https://harpd.com/developers/agents/openapi.yaml) — the same contract in YAML - [Worked examples](https://harpd.com/developers/agents/examples/) — Claude, Cloudflare Agent, OpenAI-style client, generic HTTP agent and MCP agent - [Pay Harpd in ten lines](https://harpd.com/developers/agents/examples/pay-harpd.html) — the shortest copy-paste x402 payment snippet for an agent (no signup, no API key, USDC on Base, no ETH) - [Harpd for AI Agents](https://harpd.com/for-agents/) — the agent-facing overview - [Agent trust page](https://harpd.com/for-agents/trust/) — methodology, freshness, provenance, versioning, uptime, privacy, limits and the refund policy - [MCP tool catalog](https://api.harpd.com/mcp) — `search_products`, `get_rank` (free; `rank_products` is a legacy alias), `harpd_compare`, `harpd_research`, `harpd_optimize`, `get_historical_data` (paid) Free and unauthenticated by design: `GET /api/agent/v1/search`, `GET /api/agent/v1/rank`, `GET /api/agent/v1/pricing`, `GET /api/agent/v1/manifest`. Paid per request: `POST /api/agent/v1/compare` (0.01 USDC), `POST /api/agent/v1/optimize` (0.01 USDC), `POST /api/agent/v1/research` (0.05 USDC), `POST /api/agent/v1/dataset/query` (from 0.02 USDC, priced in row bands). Every response is `{ data, meta }`. `meta` always carries source, version, updated_at, methodology, canonical, dataset, license, citation, request_id, free and payment — `payment` is `null` on a free response and the settled receipt on a paid one, so a client never has to branch on whether the key exists. `meta.citation` is a ready-to-quote attribution line. A settled payment is single-use: replaying it returns HTTP 409. An unpaid call to a paid endpoint returns HTTP 402 with the exact requirements in the `PAYMENT-REQUIRED` header. A request that Harpd already knows it cannot fulfil — a malformed body, an unknown dataset field — is rejected with HTTP 400 **before** any payment is taken. An agent is never charged for a response it does not receive. ## Open datasets (machine-readable, CC BY 4.0) - [Open data index](https://harpd.com/data/) — every public Harpd dataset, its schema and its citation line - [Objective metrics — non-sponsored](https://harpd.com/data/rank-open-data.json) — verified GitHub stars and first-party referral counts per product, each with its verification timestamp. Contains no Rank Points and no rank positions. - [Rank dataset — promotional board](https://harpd.com/data/rank.json) — rank, Rank Points, category and verification status (the paid-placement half of the data) - [Rank dataset (CSV)](https://harpd.com/data/rank.csv) — the same board as flat CSV - [Methodology](https://harpd.com/data/methodology.json) — the exact rules behind every number - [Rank rules](https://harpd.com/rank/rules/) — human-readable version of the same rules - [Discovery Index](https://harpd.com/discovery/) — non-sponsored coverage dataset of software, AI and developer products (JSON + CSV), independent of Rank Points - [Discovery Index (JSON)](https://harpd.com/data/discovery-index.json) — one record per discovered product: name, domain, category, keyword-evidence classification and the observed homepage description ## Developers (public data API) - [Developer hub](https://harpd.com/developers/) — datasets, AI access and citation surfaces at a glance - [Public API reference](https://harpd.com/developers/api/) — the read-only Harpd API: dataset endpoints in JSON and CSV, the Rank API and the per-page SEO/GEO payload. No authentication, no key, CC BY 4.0. ## Citing Harpd (CC BY 4.0 — attribution required) - [Citation formats](https://harpd.com/citation/) — copy-ready short, website, dataset, research and academic (BibTeX) citations - [Citation hub](https://harpd.com/cite/) — ready-to-copy plain-text and BibTeX citations for every Harpd dataset, each with its own data date, coverage, update cadence and licence - [Evidence register](https://harpd.com/evidence/) — every published Harpd claim resolved to its dataset, methodology, source and data timestamp; claims that fail the chain are listed with the reason instead of being hidden - [Evidence graph (machine-readable)](https://harpd.com/data/evidence.json) — the same register as JSON: claims, violations, canonical datasets and the resolved graph Every Harpd dataset is published under CC BY 4.0 and may be quoted, redistributed and reused commercially with attribution. Two rules when citing Harpd: state the "as of" data date next to any figure, and describe Rank Points as promotional placement — never as a quality score, rating or review. Modeled estimates are labelled "estimated" in the data and should stay labelled when quoted. ## Harpd Rank - [Public leaderboard](https://harpd.com/rank/) - [How to list a product — step-by-step guide](https://harpd.com/how-it-works/) - [Categories](https://harpd.com/rank/categories/) — the compact board index - [Category taxonomy](https://harpd.com/categories/) — every category with product counts, current leaders and all three board scopes - [New products](https://harpd.com/rank/new/) - [Submit and manage](https://harpd.com/rank/manage/) - [Rules](https://harpd.com/rank/rules/) - [Credits](https://harpd.com/rank/credits/) - [Historical reports](https://harpd.com/rank/history/) - [Research](https://harpd.com/research/) — monthly research reports computed from closed Rank snapshots: AI market index (whole board), AI tools index, AI tools trends, developer tools index, AI agent index - [Product Discovery Index framework](https://harpd.com/research/product-discovery-index/) — the official framework: which signals Harpd measures, how each is produced, and what each may and may not be used to claim - **Research diff engine** (`/research/diff/` — not published yet) — what changed between the two most recent closed monthly snapshots: board size, Rank Points, entrants, exits, rank movement and category share. It goes live at https://harpd.com/research/diff/ only once two comparable closed months exist, so the URL 404s until then; every figure is computed by differencing the two archive snapshots, never estimated. Baseline figures are machine-readable now at https://harpd.com/data/rank-history.json ## Ranking facts - Every approved product enters Overall Rank for free, including products with 0 Credits and 0 Rank Points. - 1 completed Harpd Credit spent on Rank creates 1 permanent Rank Point. - Overall counts lifetime completed Rank Points. - Monthly includes products approved in the current UTC calendar month plus products earning RP in that month; its score is RP earned in that month. - Weekly includes products approved in the current UTC Monday–Sunday period plus products earning RP in that week; its score is RP earned in that week. - A completed Rank spend contributes simultaneously to Overall, Monthly and Weekly. - The public Overall board includes up to 1,500 eligible listings (100 rows per page); all-products Monthly and Weekly boards show up to 100 positions. Product profiles remain public beyond the Top 100; owners can see their exact position and the #100 threshold. - Completed Monthly and Weekly results are archived with placements outside the public Top 100 retained for product history. - Verification is required before spending Credits, not for free Rank eligibility, subject to moderation approval. - Rank Points are optional promotional placement, not an editorial recommendation, rating or review, and cannot be converted back to Credits. - Position does not guarantee impressions, clicks, traffic, leads, sales or conversions. - Objective metrics are published separately from Rank Points at [harpd.com/data/rank-open-data.json](https://harpd.com/data/rank-open-data.json): verified GitHub star counts (read from the GitHub REST API, refreshed at most weekly, each carrying its own verification date) and first-party referral counts. They are observable facts about a product and are not for sale. A metric with no verified source is published as null — Harpd does not estimate or interpolate metrics. ## AI model data (open, sourced) - [Model comparisons](https://harpd.com/models/) — head-to-head model comparisons built from the pricing registry; every "cheaper" claim is computed from list prices, never hand-written - [LLM pricing table](https://harpd.com/llm-pricing/) — list prices for 16 hosted models, USD per 1M tokens, each with source and last-verified date - [Machine-readable pricing dataset](https://harpd.com/data/llm-pricing.json) — the same registry as JSON (schema documented at [/data](https://harpd.com/data/)) - [Model compare calculator](https://harpd.com/model-compare/) — side-by-side monthly cost for any two registry models at your workload - [Benchmarks](https://harpd.com/benchmarks/) — open benchmark program: methodology, datasets, limitations, reproduction; published as CSV + JSON on GitHub - [Evidence register](https://harpd.com/evidence/) — every public Harpd claim mapped to its dataset, methodology and data-derived last-updated date - [Methodology](https://harpd.com/methodology/) — how Harpd measures model pricing, model replacement and cost per successful task - [Cost per successful task](https://harpd.com/cost-per-successful-task/) — why raw token price hides the real cost of failed or retried calls ## AI cost calculators Planning-estimate calculators that run entirely in the browser, using the same sourced pricing registry as the dataset above (formula, worked example, limitations and pricing source documented on each page): - [AI cost calculator](https://harpd.com/ai-cost-calculator/) — estimate a total monthly AI bill across every hosted model we track - [LLM cost calculator](https://harpd.com/llm-cost-calculator/) — per-model API cost, every model ranked cheapest first - [AI agent cost calculator](https://harpd.com/ai-agent-cost-calculator/) — monthly bill for an autonomous agent making thousands of paid calls - [Model compare](https://harpd.com/model-compare/) — two models, one workload, cleanest price gap ## Direct answers (built for answer engines) Concise, sourced answers to the questions people and AI assistants ask about Harpd Rank, Rank Points and agent commerce. Each page leads with a quotable answer and links to the live data. - [What is Harpd Rank?](https://harpd.com/answers/what-is-harpd-rank/) - [What are Rank Points?](https://harpd.com/answers/what-are-rank-points/) - [How do AI agents pay each other?](https://harpd.com/answers/how-do-ai-agents-pay-each-other/) - [What is agent commerce?](https://harpd.com/answers/what-is-agent-commerce/) - [How much does it cost to list on Harpd Rank?](https://harpd.com/answers/how-much-does-it-cost-to-list-on-harpd-rank/) - [What are the best AI agents right now?](https://harpd.com/answers/best-ai-agents/) - [What are the best developer tools right now?](https://harpd.com/answers/best-developer-tools/) - [What are the best SEO tools right now?](https://harpd.com/answers/best-seo-tools/) - [What are the best AI coding tools right now?](https://harpd.com/answers/best-ai-coding-tools/) - [What are the best productivity tools right now?](https://harpd.com/answers/best-productivity-tools/) - [All answers](https://harpd.com/answers/) ## Harpd Apps - [Harpd Rank](https://harpd.com/rank/) — transparent public product leaderboard where tools and AI products compete on accumulated Rank Points - [SiteCheck](https://check.harpd.com/) — web developer tool to audit DNS, SSL certificates, HTTP headers and tech stacks - [Langue](https://langue.harpd.com/) — focused language lessons and voice practice ## Trust and contact - [Privacy](https://harpd.com/privacy/) - [Terms](https://harpd.com/terms/) - [Security](https://harpd.com/security/) - [Contact](https://harpd.com/contact/) ## Frequently asked questions - **What is Harpd?** A product discovery and ranking intelligence platform for makers. Its primary public product is Harpd Rank, where products submit for free and compete in Overall, Monthly and Weekly rankings. - **Is Harpd Rank free?** Yes. Every approved product enters Overall Rank for free, including products with 0 Credits and 0 Rank Points. Spending Credits is optional promotional placement. - **What is a Rank Point?** One Harpd Credit spent through the completed Rank flow creates one permanent Rank Point, counted simultaneously in the Overall, Monthly and Weekly boards. It cannot be converted back to Credits. - **Is Harpd Rank an editorial "best of" list?** No. Rank is not an editorial recommendation, rating or review. Rank Points are optional promotional placement, and position does not guarantee impressions, clicks, traffic, leads, sales or conversions. - **What is Harpd Agent Market?** A machine-readable discovery surface for autonomous agents, with a free public catalog at [api.harpd.com/api/agent/v1/catalog](https://api.harpd.com/api/agent/v1/catalog). - **What are Harpd Apps?** Standalone Harpd products: SiteCheck (DNS, SSL, HTTP header and tech stack audits) and Langue (language lessons and voice practice). Full answers: [Harpd Full Documentation](https://harpd.com/llms-full.txt) ## Current Harpd Rank leaderboard (auto-generated 2026-11-03) 941 approved products. 28 categories currently hold at least one product; the full board registry (including boards with no products yet) is at https://harpd.com/data/categories.json. 1 product currently holds Rank Points (268 total). Source: https://harpd.com/data/rank.json (CC BY 4.0). Rank Points are promotional placement, not an editorial quality score. Ranked leaders (Overall board, by Rank Points): 1. imgkit — 268 Rank Points — ai-media — https://harpd.com/rank/imgkit-86d32f3e/ Categories with live boards: - other (245) — https://harpd.com/rank/category/other/ - developer (106) — https://harpd.com/rank/category/developer/ - ai-media (100) — https://harpd.com/rank/category/ai-media/ - agents (65) — https://harpd.com/rank/category/agents/ - marketing (47) — https://harpd.com/rank/category/marketing/ - seo (45) — https://harpd.com/rank/category/seo/ - productivity (44) — https://harpd.com/rank/category/productivity/ - audio (39) — https://harpd.com/rank/category/audio/ - business (29) — https://harpd.com/rank/category/business/ - design (27) — https://harpd.com/rank/category/design/ - hiring (23) — https://harpd.com/rank/category/hiring/ - education (21) — https://harpd.com/rank/category/education/ - health (19) — https://harpd.com/rank/category/health/ - writing (18) — https://harpd.com/rank/category/writing/ - directories (17) — https://harpd.com/rank/category/directories/ - sales (14) — https://harpd.com/rank/category/sales/ - games (13) — https://harpd.com/rank/category/games/ - travel (11) — https://harpd.com/rank/category/travel/ - social (10) — https://harpd.com/rank/category/social/ - ecommerce (9) — https://harpd.com/rank/category/ecommerce/ - leaderboards (8) — https://harpd.com/rank/category/leaderboards/ - security (7) — https://harpd.com/rank/category/security/ - crypto (5) — https://harpd.com/rank/category/crypto/ - domains (5) — https://harpd.com/rank/category/domains/ - news (5) — https://harpd.com/rank/category/news/ - agencies (4) — https://harpd.com/rank/category/agencies/ - real-estate (4) — https://harpd.com/rank/category/real-estate/ - people (1) — https://harpd.com/rank/category/people/ Machine-readable: /data/rank.json, /data/top-products.json, /data/market-index.json, /data/categories.json, /data/rank-history.json, /data/methodology.json, /data/answers.json, /data/comparisons.json, /data/alternatives.json, /data/research.json, /data/evidence.json, /data/claims.json, /data/citations.json Immutable periods: /data/rank/latest.json (newest closed month), /data/rank/{YYYY-MM}.json (one frozen month, never rewritten), /data/rank/snapshots.json (index), /data/changelog.json (what changed between snapshots). How the ranking works: https://harpd.com/rank/methodology/ — Rank Points are promotional placement purchased with Credits, not an editorial quality score or a review rating. Data documentation: https://harpd.com/docs/data/ — datasets, API, schema, snapshots, licence, citation, embeds and usage examples in one page. How to cite: https://harpd.com/data/citations/ — a ready-to-paste citation per dataset (plain text, Markdown, HTML, APA, BibTeX).