# FAQ Answers to common questions about the Rarebl Open API. ## Getting started ### Which SDKs are there? Single-file SDKs for [JavaScript](https://docs.rarebl.com/sdks/js), [Python](https://docs.rarebl.com/sdks/python), [PHP](https://docs.rarebl.com/sdks/php) and a [shell](https://docs.rarebl.com/sdks/shell) tool. They generate keys, build and verify transactions, sign locally and verify webhook signatures. Each download page shows its SHA-256. ### Do webhooks need an account? No. `hooks/create` returns a management token and a signing secret, shown once. Deliveries are signed with `X-Rarebl-Signature`. See [Webhooks](https://docs.rarebl.com/guides/webhooks). ### Do I need an API key? No. The API is keyless and has no accounts or billing: clients are limited per IP, by rate class. The `X-API-KEY` header is reserved and ignored. See [Authentication](https://docs.rarebl.com/authentication). ### Can I call the API from a browser? Yes. The API sends `Access-Control-Allow-Origin: *`, so browser apps can call it directly, and the Try It panel on every endpoint page does exactly that. ### Should I use GET or POST? Both work with identical parameters. `GET` with query parameters is simplest. `POST` takes the same parameters as a JSON body. ### Is the API stable? The Open API (v1 and v2) is live at `https://api.rarebl.com`. The endpoint paths and the response envelope are the contract, and the [Changelog](https://docs.rarebl.com/changelog) records every change. ### Is there a Postman collection? Yes: download [the collection](https://docs.rarebl.com/collections/rarebl-api.postman_collection.json) and [the environment](https://docs.rarebl.com/collections/rarebl-live.postman_environment.json) and import both into Postman. It covers every endpoint, with folders by group, POST bodies and headers, and variables for the webhook id and token. ## Data and chains ### Which chains are supported? Bitcoin (`btc`), Litecoin (`ltc`), Bitcoin Cash (`bch`), Dash (`dash`), Ethereum (`eth`, with ERC-20, ERC-721 and ERC-1155 tokens) and TRON (`tron`, with TRC-10, TRC-20 and TRC-721 tokens). See [Chains & units](https://docs.rarebl.com/chains-and-units). ### Where does the data come from? From Rarebl's own full nodes. There are no third-party chain APIs behind the Open API, and the [Rarebl Explorer](https://docs.rarebl.com/explorer) uses the same data, so the two always agree. ### Can I send transactions? Yes, with Open API v2: [Build](https://docs.rarebl.com/api/tx/build), sign, [Assemble](https://docs.rarebl.com/api/tx/assemble) and [Broadcast](https://docs.rarebl.com/api/tx/broadcast), on all six chains including USDT on ETH and TRON. The safest way is to sign on your own machine with an [SDK](https://docs.rarebl.com/sdks/python). Smart-contract calls beyond token transfers, logs and an RPC proxy are not part of the Open API. See [Send a transaction](https://docs.rarebl.com/guides/send-a-transaction). ### Do I have to send my private key to the API? Hosted signing (`tx/sign`, `tx/send`, `address/new`) sends your private key to Rarebl over TLS, and needs the header `X-Rarebl-Accept-Risk: hosted-signing`. Signing locally with an SDK keeps keys on your side and is recommended. See [Hosted signing](https://docs.rarebl.com/guides/hosted-signing). ### Are the market prices trading rates? No. They are reference prices aggregated from public exchange feeds (the median of fresh sources), not Rarebl trading rates. See [Market data and fees](https://docs.rarebl.com/guides/market-data). ## Limits and freshness ### What are the rate limits? Per IP and by class: reads 5 per second (burst 20), compute 2 per second (burst 10), write calls such as broadcast 6 per minute (burst 3, 300 per day), watch 30 per minute, hooks 10 per minute and 3 stream connections. Past a limit you get `API429` and a `Retry-After` header. See [Rate limits](https://docs.rarebl.com/rate-limits). ### How fresh is the data? Chain heads in [Live stats](https://docs.rarebl.com/api/stats/live) are at most about 2 seconds old. See [Data freshness](https://docs.rarebl.com/data-freshness) for the other endpoints, confirmations and reorg depths. ### How many confirmations should I wait for? That is your policy. The API treats data deeper than the reorg depth as settled: 6 blocks on BTC, LTC, BCH and DASH, 64 on ETH and 20 on TRON. See [Track a deposit until it confirms](https://docs.rarebl.com/guides/track-a-deposit). ### Why do I get API409? The data is not available yet on that chain. `data.reason` says why: the history index is still being built (`history_unavailable`), the ETH node is still syncing (`tx_index_pending`), a TRON height is before 2026-09-08 (`before_history_start`), or there is no mempool view (`no_mempool_view`). See [Coverage and limits](https://docs.rarebl.com/limits-today). ### Why is a Bitcoin, Litecoin or Bitcoin Cash balance null? Those balances need the history index, which is still being built. The address reply says `balanceStatus: "index_pending"`. `null` means unknown, not zero. DASH, ETH and TRON balances are exact. ## Support ### Where do I get help? Email [hello@rarebl.com](mailto:hello@rarebl.com) or message us on [WhatsApp](https://wa.me/233551648687). Include the request you sent (with the `chain` and the hash or address) and the full reply, `code` and `message` included. ### Do these docs track me? We count page views without cookies; no personal data. The counts use no cookies or stored identifiers and respect Do Not Track and Global Privacy Control. Nothing you type into Try It, no request body, address or hash is ever sent to analytics. ### Do I need a Rarebl account? Not to use the Open API. You can [sign up](https://app.rarebl.com/#!/signup) for the Rarebl app, which is a separate product from this API.