- Cryptocurrency exchanges
- Block explorers
- Fee estimation services
- Transaction decoders
- Transaction broadcasters
- Optical Character Recognition (OCR) services









These allow you to buy / sell / send / receive bitcoin.


Solidi (solidi.co)









These allow you to look up information about the Bitcoin blockchain. Examples:
- The balance in a Bitcoin address.
- The transactions related to an address.
- The unspent outputs stored in an address.
- The status of a transaction (broadcast, mined, number of confirmations).


BlockCypher:
live.blockcypher.com


Blockchain.com:
www.blockchain.com/explorer


For looking up the details of unspent outputs (UTXOs) in a Bitcoin address, you can use this recipe:
Recipe for looking up the unspent outputs in a Bitcoin address #2

The linked recipe relies on a particular feature of a specific block explorer (Blockchain.com). If that feature is discontinued at some point in the future, you can use the previous version of that recipe, which requires more manual work, but can be used with any block explorer. Link:
Recipe for looking up the unspent outputs in a Bitcoin address


To look up the status of a transaction, you can search for its txid using a block explorer's search field.
- If the transaction has been received by the service but has not yet been mined, it will be displayed with a message similar to "Confirmations: 0/6".
- If the service has not seen the transaction, you will get a search result similar to this:
"No transaction found with the hash
bf7a16ef4bf8763b7bf7f02b03155c9a2f9b997d19e64a770bf3f7d3f24cc480"
- You can refresh the page to re-check a transaction's status.


For looking up the raw hex form of a transaction:
- BlockCypher: On a transaction page e.g. you can click Advanced Details / API Call, which produces a raw text dump of the transaction.
- Blockchain.com:

Example:
blockchain.info/tx/db2c3d84708cd9d0e40ae1754021f9146a0d6ab555fc0e1d547d7876c0c092f4?format=hex









These estimate how long you will wait for a transaction to be mined, depending on its fee rate in satoshi / byte.

Earn.com:
bitcoinfees.earn.com









If the service can successfully decode a transaction, this indicates that the transaction is formatted correctly.


BlockCypher:
live.blockcypher.com/btc/decodetx









These allow you to broadcast a signed transaction to the Bitcoin network.


BlockCypher:
live.blockcypher.com/btc/pushtx









These can be used to extract plaintext from PDF scans.


OCRSpace:
ocr.space


OCRConvert.com:
www.ocrconvert.com