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Bitcoin wallets: an intro for developers

Are you curious about what you can build on Bitcoin using well established programming languages and frameworks?

Our introductory course to Bitcoin Development course is tailored for application developers, blockchain developers, and even those with little or no programming experience with Bitcoin looking to start developing on Bitcoin.

To give you an idea of what to expect from this free, certificate course, curriculum creator, Evan Freeman offers you this course preview.

An introduction to Bitcoin wallets

Typically, the creation of a Bitcoin transaction and storing of Satoshi tokens (bitcoins) are performed by a software for key management called a wallet. Additionally, a wallet can provide functions related to creating and sending transactions, sending messages with the encryption using the same keys which are locking the coins, and many other actions depending on how advanced the wallet software is.

What types of Bitcoin wallets are there? Custodial Bitcoin wallets

There are different types of wallets, as well some that even store the keys on the behalf of users, becoming custodial wallets. Most cryptocurrency exchanges perform this role of being custodian of their users and are custodial wallets.

Non-custodial Bitcoin wallets

Others which provide a Software for users to install and use are non-custodial wallets like the ElectrumSV and HandCash wallets.

Web-based Bitcoin wallets

There are also wallets like MoneyButton’s wallets for which you don’t need software as they are web-based products. All the same, such a wallet will still require users to own and store their Bitcoin keys (or the seed phrase used to generate the keys) and continue to stay non-custodial wallets.

Simplified Payment Verification (SPV) wallets

In Bitcoin SV, there are also wallets that qualify as SPV wallets. In short, an SPV is a lightweight client which only stores the block headers and merkle roots which are the only things needed for verification of a transaction being valid or not. More details about the SPV client are provided in the BSV wiki.

More about SPV

SPV is most useful for proving that a payment happened. Especially when small value payments are confirmed instantly (zero-confirmation) this happens due to an SPV check or SPV proof that ensures the merchant taking the payment that this is not a double spend and it is a valid payment to accept, even though it is either yet to be mined or processed in a block by the mining network.


For large value payments, it is still advisable to wait for few block confirmations so as there is no possibility of the transaction being lost in orphan blocks. To learn more about SPV and other payment protocols, register for our introduction to Bitcoin Development course

Bitcoin wallet functionality

Wallet clients typically provide not just key management, but also transaction management capabilities. They will abstract most of the low-level functionality of building a transaction using the user keys and allow for a similar user experience that any payment wallet does. Once the transaction is created, the next step will be for the user to broadcast this transaction to the Bitcoin network.

This is done either by the user directly broadcasting the transaction (if using a SPV wallet) or the wallet service provider broadcasting it on the behalf of the user.

Typically, the wallet service provider will have a few selected nodes which they will broadcast these transactions to and then it is the responsibility of the node to propagate the transaction to the rest of the node network.

Bitcoin network participants and role division

An important concept to note is that the node network is hyper connected with each other, so the overall propagation of transactions happens quite quickly (milliseconds or less).

Graphic: User broadcasts transaction to a node, then the node propagates across the network
Graphic: User broadcasts transaction to a node, then the node propagates across the network

The graphic above shows the broadcasting and propagation of a transaction to the Bitcoin network. At the centre of the network is a hyper connected (small world) network of nodes which are the mining or transaction processing nodes.

Bitcoin miners, or transaction processors

The real transaction processors are only the nodes that produce blocks, not even all the nodes which are participating, as only the ones that produce blocks are contributing to the updating of the ledger. You can read more about the difference between a Bitcoin node and a miner over here.

There is one more concept of block difficulty adjustment which happens approximately every 2 weeks, which metaphorically means that the game of mining and finding the puzzle solution is reset and restarted every 2016 blocks or about 2 weeks. This means that only the nodes that are able to produce a new block in this window matter to the Bitcoin network, none of the other nodes really count as a miner or transaction processor.

Bitcoin users

The users form the outer layer in the network, which are connected to one or more nodes. This effectively makes the network distance between two user nodes a max of 3 and the network distance for a broadcasting transaction of 2 hops or maximum of 3.

Integrating a Bitcoin wallet into your app

When building an application where there are users from across the globe creating and sending transactions, it will typically be done either using a wallet service or doing this work of broadcasting in the application itself (this will mean the application will be hosting a wallet service as well).

On the other hand, for different types of applications which focus on reading the Bitcoin ledger, you can easily build things like event listeners which can listen to transactions with specific attributes that the application has, identifying them for an action or future reference. But this can be flipped around as well, where it can be an application that monitors the Bitcoin network for certain types of transactions generated by other applications and can build use cases around them.

One good example will be a visualisation application for social media networks storing all transactions on chain (on the Bitcoin ledger). This new visualisation uses other application data but builds its own social media network version of it. There can also be applications using other applications data referenced for various purposes, for example a location based social media network which needs to show weather data for that location, can use the data stored on the bitcoin ledger by an application which purely stores weather data for a large number of locations across the globe. These are just a few basic examples, but there are and will be large consequences of these kinds of properties in future to come.


An introductory course to Bitcoin development

If you’re interested in learning more about Bitcoin development, you’re sure to benefit from the  BSV Academy’s free introduction to Bitcoin development course.

In particular, it will focus on a series of short introductions to commonly used development tools in the space, with practical implementation assessments after each chapter.

To sign up for this free course, head over here.

Evan Freeman
Evan Freeman

Bitcoin Curriculum Specialist