Running bitcoin client without downloading the entire blockchain

Console Client and GUI Client

bitcoind is the client that you can run in headless mode (com.mand line).  bitcoin-qt is the GUI based client.

Do I need to download the entire blockchain to get the client working?

In short, yes. However, there is a way to ‘prune’ the downloaded chain. i.e. You can set a specified size – and the chain will not exceed the pre-allocated space on your disk (i.e. – of you set your limit to 400 GB, the pruning will only use 400 GB and still manage to validate your wallet’s transactions). From bitcoin’s documentation:

Block pruning works by deleting block files “as you go” – whenever disk space is allocated. Thus, if the user specifies 550MB, once that level is reached the program will begin deleting the oldest block and undo files, while continuing to download the blockchain.

However, since you are running a pruned version, there’s several things you will not be able to do against the local chain (such as search for just any transaction).  So – if you can’t do it against the local blockchain, what is your alternative?

Enter API Service

To have access to the entire blockchain, call an API that is hooked into the chain.

On your client machine, keep running your minimal client (pruned client). Simply have the client call the API service.

This way, you still have access to the entire blockchain – and can perform any operation you like.

There are several companies offering APIs that plug into the mainnet.  Blockchain dotcom’s a popular one (look for ‘Wallet API’ in the list of APIs).  There’s also a websocket version of the API – which can send notifications on payment events.  BitPay and Coinbase also offer APIs – but blockchain.com is  heavily used by developers.

Summary

There isn’t really a way to run a bitcoin client without downloading the entire chain, but there are some workarounds. You can run a pruned version of the chain locally, and use your local client to call an API  service. The API service provides you with full access to all the blocks on the main chain.