Launched recently, the new Unchained app provides Unchained clients the fastest and easiest way to purchase and deposit bitcoin directly into multisig cold storage on the go.

Over the last year, a mobile app has been one of the most highly requested new products. On X (formerly Twitter), via email, phone, or at in-person events, clients let us know that they wanted an Unchained mobile app. The launch of the Unchained app, which is now available on iOS, marks a significant milestone for Unchained because it is our first step towards providing clients with a mobile-first experience.

In this article we’ll cover our overall mobile strategy, the research that went into the app, the challenges we faced, and future plans for the Unchained mobile app.

Strategy

At Unchained, for every major release, we follow a 5-phase development process: 

1. Strategy: Why are we building the feature?
2. Discovery: Spec out exactly what we’re building
3. Build: Get to coding
4. Acceptance: Test the new the feature
5. Delivery: Take the feature to market

Before embarking on any discovery related to how our flagship mobile app might work, might look like, or what features we were going to bundle into it, we needed to have a clear strategy defined for what we wanted an Unchained mobile app to accomplish.

Setting a strategy is important because, as Will Cole mentions in his Think, Then Do series, figuring out what the requirements will be to deliver on the strategy may be the hardest part.

The necessary requirements to deliver on the strategy may be the hardest part. Our goal is to figure out what is essential while not being prescriptive. The reason is that there is endless creativity, testing, and iterative loops in figuring out exactly what needs to be done, and that is a lower level of abstraction.

Strategy helps us set the initial scope, but more importantly, tells us what not  to pursue in order to get our app to market. We decided that our strategic product goals were to start small and offer a premium, world-class experience for a set of core functionality that:

• Made it easier for clients to buy bitcoin through Unchained.
• Our clients have already expressed interest in.
• Functionally makes sense to include in a mobile experience.
• Enhances the overall experience of Unchained products.

These strategic product goals immediately helped shape many initial decisions; an important one being that mobile would not reproduce the full suite of functionality available in the Unchained web application. For various reasons that will be expanded on later, we freed ourselves from having to rebuild the full application for the initial rollout of the mobile experience.

Determining the initial scope

Gathering Insight

With a strategy in place, it was time to start executing, which happens during the discovery phase. In discovery we’ll do research, identify client needs, requirements, and build specifications around those requirements with feedback and oversight from stakeholders. All of this pre-planning happens before anything is put into code.

While we had a lot of anecdotal evidence that clients wanted a mobile app, we didn’t have insight into exactly what they wanted, so we started by surveying a selection of our most active clients.

The results of this feedback were fantastic because they immediately started to guide where we might take the app. The top three results, unsurprisingly, matched the type of clients we partnered the most with at Unchained: The long term bitcoin saver.

Now we had a clear list and order of what was most important for this persona:

To key or not to key

When developing mobile bitcoin applications, you’re inevitably going to run into the question of what to do about private keys. Our initial survey gave us some insight into how we should prioritize adding keys and allowed us to think through whether or not to include a mobile hot key. 

Creating cold keys

Creating keys, a required step for building multisig wallets, was lower on the list of priorities for our surveyed clients. Not needing to include the ability to add keys via mobile helped us narrow the initial scope significantly. At the moment, Unchained supports Ledger, Trezor, and Coldcard for securing bitcoin in vaults. We support these devices via a direct connection to a laptop (and air-gapped for Coldcard), but we do not yet support mobile/QR based key import.

While we could have done some sort of “movie magic” with a mobile-to-web handshake in the processes of creating keys and signing transactions, we thought this experience went against our strategic goals. Clients would need to start these processes on mobile, but then ultimately connect their devices to a laptop or computer in order to finish, before again coming back into the app. We determined that the mobile-to-web approach neither felt like a premium experience, nor did it meet our strategic goal of only initially building out features that made sense the context of the inherent limitations of a mobile app.

What about mobile hot keys?

We considered a mobile hot key feature to simplify the process of creating keys and vaults directly within the app. However, Unchained strongly advises generating keys on hardware wallets so that they never come in contact with the internet, which is what makes them “hot.” Hot keys significantly broaden the risk of remote cyber attacks, potentially enabling attackers to access the key information. This option would also mean that clients would need to further trust that Unchained wasn’t doing anything nefarious in the key generation process. We are open to considering this option again in the future, but we don’t feel this option meets out high security bar, and thus decided against it for now.

Unchained believes that key generation offline via hardware wallets is the most secure option for people who are primarily focused on securing their life savings for generations. Within this design constraint, we decided to focus our efforts on a mobile friendly approach that leverages three cold keys to start. 

Decision

We concluded the discovery phase by limiting our scope to the following features: 

1. Buy bitcoin directly to cold storage 
2. Deposit bitcoin to vaults
3. Track balances and portfolio value 
4. Mobile push notifications for events that required a client’s attention 
5. Biometric authentication for easy sign in and more advanced security
6. Account lock-down in the event of a suspected attack. 
7. Enable support pin access for quick anti-phishing verification

While the second half of the list did not come directly from survey responses, they were features that we knew would elevate the client experience and keep clients more secure. Notifications are a critical component of any mobile app, and in the case for products built on bitcoin, email and in-app notifications can be critical to securing wealth. Leveraging mobile push notifications provides us a much more direct and streamlined way of updating clients in a timely manner, which allows clients to take immediate action when needed.

Unchained is uncompromising in our commitment to providing best-in-class security. Biometric authentication and in-app locking provides another additional security measure that could delight our clients and further protect their accounts. We also wanted to make sure that clients on mobile could quickly access our support PIN feature, so that they could quickly verify the identity of an Unchained employee anytime they were on a phone call with them, and prevent falling for any would-be phishing attack.

Focus on native iOS development

The most critical decision we had to make during discovery was which platform to build the app for initially. The decision was in part guided by the strategic principle mentioned earlier that we wanted to offer a premium, world-class experience for mobile. In order to deliver a world-class bitcoin experience, we knew we’d want to have access to core features like biometrics, NFC, bluetooth, and camera capabilities, all from a highly performant app. 

These are considerations because iOS has a lesser diversity of devices to ensure compatibility and performance with as compared with Android, but it was also important when weighing whether to build on iOS natively, as opposed to React Native or a progressive web app. . 

Biometrics could provide clients ways to quickly and reliably authenticate themselves in the app, and could be used in the future as another security layer in the transaction signing flow, or a whole host of other bitcoin-related activities like vault rekeys. And as we look to solve for the mobile-first multi-hardware wallet approach, we’d need to be able to work with devices that supported functionality over NFC, bluetooth, or QR scanning.

Using the native tools on iOS to seamlessly work with these tools ruled out using a library like React Native or Flutter (which would have allowed us to develop for both iOS and Android simultaneously) because these libraries require using other third party libraries to leverage many of these features. React Native apps usually lag behind in their ability to adopt the latest and greatest native tools, and usually don’t perform as well as what you get out of the box from native iOS and Android development due to these third-party dependencies.

We also considered building a progressive web app (PWA). Apart from sharing some of the similar issues that React Native apps have, PWA’s have the added issue that they’re not discoverable on the iOS App Store. Unchained won’t compromise on performance and availability, so that ruled out both PWA’s and React Native apps. Given the inherent design challenges we face building collaborative custody on top of bitcoin, we needed to ensure that we would be able to work with the performant stack as possible. 

Given that we knew we wanted to build natively, we ultimately decided on going iOS first because most of our site traffic was iOS-based. Focusing on iOS only allowed us to ship a mobile experience quicker, gather early learnings from our iOS cohort, and gauge the interest in an Android offering. This decision gave us the time to figure out the right strategy for a sharded development process between iOS and Android. Developing for iOS also pushed our engineers to revamp the backend infrastructure to be more easily repurposed for an eventual Android launch. If and when we do start building for Android, the new backend will help us bring an Android app to market much faster.

Launch 

The mobile app had three distinct launches, each with their own respective launch objectives. Each of these launches were important to us, for varying reasons, and ultimately led to the final, production launch currently available on the app store today.

Internal beta

The first launch was an internal beta exclusive to Unchained employees. The goal was to have Unchained employees push the app to its limits, help us uncover any bugs, UI/UX issues, and polish the app to the standard that our clients expect. The internal beta period ran for a number of weeks and included several rounds of app updates and fixes. This launch was particularly important because we had experts from varying backgrounds within the organization interacting with the app and filing bugs for improvements we could make.

It was during this period that we added the vault deposit recommendation amount. This is a particularly interesting problem space for us on mobile, since we build products on top of P2SH multisig. Deposits to vaults were going to be significantly easier to make, so it was more likely that clients would make more frequent deposits on mobile. While on the surface this is a positive outcome, we had to ensure that we were still protecting our clients and ensuring that they were following best practices for UTXO management, and preventing UTXO’s from becoming dust in the future. These are the types of particulars that we were able to cover during the internal beta that helped to elevate the in-app experience.

By the end of the internal launch period, we felt the app had been pressure tested sufficiently enough to move onto the next launch phase.

Signature Exclusive

The second launch phase was our exclusive launch period for Unchained Signature clients. One of the benefits of Unchained Signature is early access to new products and features. The goal of this Signature period was to gather feedback from clients who are in deep partnership with Unchained. This period confirmed some of our goals and highlighted some areas for improvements.

Through our conversations, we gathered that the buy experience on mobile was significantly quicker and easier to access than on web, and these clients were more likely to buy on mobile than on web moving forward. Additionally, Signature clients expressed that they enjoyed how easy the app was to use, and that they enjoyed the price notifications because it was a nice trigger for them to smash buy in the event of a significant price change.

We learned that we needed to present balance information from various account types in one holistic view. Unchained Signature comes with multiple account types, such as a personal, trust, and IRA account. It would be nice to be able to view all this information from one place upon opening the app. We’ll be exploring a solution to this on mobile and web in the near future, along with addressing other feedback that Signature clients provided. Overall the feedback was very positive, and apart from minor improvements we made, we were ready to go live.

The third launch is the now live: public launch. We hope to hear from our early users. Feel free to send us enhancement ideas and feedback, and let us know if you spot any Easter eggs!

Future

The Unchained mobile app represents a significant leap forward in the company’s commitment to providing its clients with a seamless, mobile-first financial experience. As we move forward, we will continue to concentrate on delivering core functionalities that make it easier to work with collaborative custody and the stack of bitcoin-native products and services we’ve built on top of it.

Most importantly, we plan to expand the app so that clients can generate keys via external hardware wallets and create a vault, without needing to plug in a device or interact with a desktop client at all during the process. We’ll be working on finding devices and partners that can enable us to deliver a world-class, mobile first, user experience without the need for a dedicated hot key.

In the future you can expect some new additional features and functionality, including, but not limited to: 

• Android app
• Casting approvals: For businesses, we’ll enable approval voting on business critical operations such as new transactions, user edits, and settings changes 
• Widgets: A series of mobile widgets for quick view access on important bitcoin metrics. 
• Mobile onboarding: Enable new and existing clients to open new accounts with us via mobile. 
• Signature: Exclusive mobile experiences and perks. 
• Enhanced trading views and trading information. 
• Enhanced authentication and security: Passkey support and in-app video verifications. 

Please reach out and let us know what you think of the Unchained mobile experience. If you’re interested in joining a team building on bitcoin, check out our careers page.