Show HN: HCB Mobile – financial app built by 17 y/o, processing $6M/month
hackclub.comHey everyone! I just built a mobile app using Expo (React Native) for a platform that moves $6M/month. It’s a neobank used by 6,500+ nonprofit organizations across the world.
One of my biggest challenges, while juggling being a full-time student, was getting permission from Apple/Google to use advanced native features such as Tap to Pay (for in-person donations) and Push Provisioning (for adding your card to your digital wallet). It was months of back-and-forth emails, test case recordings, and also compliance checks.
Even after securing Apple/Google’s permission, any minor fix required publishing a new build, which was time-consuming. After dealing with this for a while, I adopted the idea of “over the air updates” using Expo’s EAS update service. This allowed me to remotely trigger updates without needing a new app build.
The 250 hours I spent building this app were an INSANE learning experience, but it was also a whole lot of fun. Give the app a try, and I’d love any feedback you have on it!
btw, back in March, we open-sourced this nonprofit neobank on GitHub. https://news.ycombinator.com/item?id=43519802
HCB is an amazing Rails 8 app. It is the Rails app that is processing $6M/month.
https://github.com/hackclub/hcb
Excellent work on the mobile app though I would wonder, since HCB runs on Hotwire, why it was not written as a Hotwire Native app which would leverage the existing Rails Hotwire app and not require a complete rewrite?
Hotwire Native tbh wouldn't have been a bad choice at all to use tbh. Especially if you wanna maintain 1:1 parity with the website. It combines both being a "web app" and native features we could still use like Tap to Pay and Push Provisioning. The downsides of it is that it isn't a cross platform framework like React so all changes would have to be pushed to both an iOS app repo and an Android app repo. Another downside is that it isn't a "write once run anywhere" type application as you're integrating Hotwire into the native code so you have to be comfortable with both Kotlin and Swift (however if you're writing native modules in React Native same applies).
Both are 2 completely valid and separate paths you could take when building an app and I'd actually be curious what'd HCB Mobile look like if we did use Hotwire Native.
The OP built the React Native mobile app - not the entire platform / company. Some folks commenting like they built the company. Just a point of clarification.
Great work! Keep building OP!
The OP title seems a bit misleading notwithstanding this caveat.
I think there's ambiguity. An app built for a platform that does xyz. Does the app do xyz, the platform, or both? If I build an app that takes you straight to idk a Treasury department website, have I built an app for a platform that transacts trillions of dollars?
seems like this is par for course for hustler “founders” nowadays to say half truths to seem groundbreaking to get attention
True. But willing to cut anyone under 21 some slack.
I thought that at first too, but then I figured it's pretty impressive that the app is processing $6M/month even though the financial platform pre-existed.
For something in the financial space, I don't see much (or really, any) tests in the code repository. CI also only has ESlint and prettier running.
How are you ensuring the application will remain maintainable in the future, you are not breaking existing stuff and integration with the actual platform is always up-to-date?
In short, what's the testing strategy for something that claims to deal with $6M a month?
If there is none, you likely want to read up a bit on things like Testing Pyramid, automated test strategies (unit-, integration- and end-to-end testing).
I am surprised you managed to get those entitlements at all!
Did it help to be a non-profit?
Tbh not at all, the process is tedious but pretty straightforward if you understand the requirements. Apple is did throw at me a huge checklist to finish which did take a while to complete, but after you successfully build the feature and submit test case videos to them its only a matter of time until you receive access to it. For Tap to Pay on iPhone, its very easy to achieve development status if you're just curious about the technology and its applications. Its more the production entitlement in which you must complete the specifications I mentioned before.
No offense to the OP (what you did is great - as someone who had to pick up expo/RN on the fly for my newest job, it can be a bit annoying, and that is before all of the compliance nightmares associated with push provisioning) but the title does seem a bit disingenuous - it is phrased to make it sound like the app he built specifically is processing $6M/Month, where it is actually the platform that the app was built for that is
This is great!
I'm curious whether you were able to build the app using backend APIs that were already built, or whether building this app created new requirements for those APIs?
Hi! Thank you so much for your kinds work :)
I actually did have to end up creating most of the backend APIs myself too or with the help of fellow engineers at HCB! What I like about HCB Mobile is that I'm not only creating a mobile app but also expanding our API infrastructure to allow for future integration with our platform.
Wow that's great experience.
My son is 9yo and loves to make little animations in Scratch. He recently started to learn a bit of Python (just the syntax so far, no projects).
I wonder whether you can share anything about your journey, especially if you have any tips for the stage my son is at.
That's great to hear your son is starting at such a young age! From my personal experience I would recommend focusing more on the concepts (which Python helps with as the syntax is easy to navigate!). Project-based coding is my ideal way of learning as you build things you are truly proud of. I remember when I was young and made my very first Python turtle drawings. Once he turns 13, I highly recommend him join the Hack Club community. Hack Club is our parent organization and its dedicated mission is to help teenagers interested in coding. I believe I wouldn't be where I am today without it. It truly helped me become a better programmer and Hack Club even offers free prizes that help you learn even more such as a Raspberry Pi for those who submit their incredible projects :) Hope that helps! Always down to help if you have anymore questions
What is this page of transactions for? https://hcb.hackclub.com/hq/transactions
I get that you want to be "open", but is everyone involved in these transactions ok with them being shared? Even if they are, this doesn't seem like a good idea security wise. I see partial account numbers and other IDs/numbers that I assume you'd prefer not be public, regardless of how insensitive they may seem now.
EXPENSIFY, INC. VALIDATION XXXXXX5987 THE HACK FOUNDATION +$0.89
FRONTING $10,000 TO CHRIS WALKER FOR GITHUB GRANTS MADE FROM PERSONAL ACCOUNT -$10,000.00
CHECK TO LACHLAN CAMPBELL +$800.00
Transfer to Emma's Earnings -$1,923.08
Hi @cirrus3,
You've found an optional feature called Transparency Mode!
I admit, this is A LOT of information being made accessible. We at Hack Club (the nonprofit organization behind HCB, and the owner of the transactions above) have chosen to make our finances publicly available on the internet. You can read more about it here: https://blog.hcb.hackclub.com/posts/transparent-finances-opt...
That link (https://hcb.hackclub.com/hq/transactions) shows our donations and spending down to the cent since we believe donors deserve to know what their contributions are funding. As a nonprofit, you can talk about what you’re spending money on, but transparency in every transaction builds trust for supporters. This level of transparency is definitely atypical, and I can see why it may raise concerns.
Other organizations using HCB (such as Reboot) can choose to enable this feature too (it's off by default), and they're briefed on the potential risks and level of exposure to decide whether it's right for their organization/team. HCB supports 6.5k nonprofits, and roughly 64% of organizations have chosen to enable this feature.
> I see partial account numbers and other IDs/numbers that I assume you'd prefer not be public, regardless of how insensitive they may seem now.
> EXPENSIFY, INC. VALIDATION XXXXXX5987 THE HACK FOUNDATION +$0.89
Good catch! Thanks for flagging that verification deposit. I've pushed a fix here: https://github.com/hackclub/hcb/pull/12336
As for the account numbers (e.g. XXXXXX5987) visible in some transactions, these are our own defunct operating accounts, and we're aware they're out there on the internet. We have a new way of managing account numbers via Column.com, so these older transactions are less of a concern for me.
I very much appreciate you bringing these to my attention! We're always looking to improve, so I'd love to hear if you find anything else.
Not just for hack club - but transactions for another organization that is using their software is public. https://hcb.hackclub.com/reboot/transactions?page=13
Not sure if all the organizations using their software know this.
They have this page for reporting: https://github.com/hackclub/hcb/blob/main/SECURITY.md
It's a hack job...
Please look at this @mohamad08
The numbers and amounts used for account validations and adding it to be able to pull or push money . Should not be shown public..
This is very helpful to the community. Great work.
Was just looking at this the other day for personal reasons. Great work!
I really wish something like Hack Club existed while growing up, how empowering! great work.
That's awesome, and impressive you were able to build that. As an angel investor, my first question would be: how do you deal with financial fraud? Like users exploiting your app for money laundering via donations then spending... Any system that lets money get in and out is eventually used as a channel by launderers.
Imagine all of the well connected and wealthy parents behind the scenes that enable this to happen.
The average person like you or me would never get the approvals rammed through at Google.
My parents nor did any parent step in to help me on this application or the approval processes. Furthermore, the approvals didn't get "rammed through". It took me quite a bit to actually acquire their entitlements and app review approval. I dislike when people assume just because I live in "Silicon Valley" I automatically have everything handed to me. If you would like to learn more about how the processes that I took to achieve this feel free to ask!
I would – as an admirer.
Please don't be cynical on HN. It's not what this site is for, and destroys what it is for.
https://news.ycombinator.com/newsguidelines.html
Why does it matter how old is the author?
We should judge software by the quality, not by authors age.
It's an age-old convention, a way of supporting and encouraging kids, and harmless.
>It's an age-old convention....
Bonus points for the wordplay.
HN isn't a judge of software; it's a place to learn and be curious. So people are often interested in projects that do a novel thing in a normal way, or a normal thing in a novel way. Eg, stories fascinate us because something was built by a very lean team, or a group with no money, or somebody who is an industry outsider, or a parapalegic, etc. Overcoming these limitations is a sort of 'hacking'.
There is a new trend in Silicon Valley of bragging about how young founders are, etc. along with the rather bizarre trend of bragging about dropping out of high school to "found a startup".
Always has been.
It is a deliberate advertisement to VCs to find "the next Mark Zuckerberg" which the entire point is that there is only one.
For every 1,000+ startups there is exactly only *one* exceptional founder.
It's quite remarkable that such a loosely quantified pool of startups (1000+) yields precisely one exceptional founder.
Totally agree. Even if I'm a teen myself I never post my age unless someone asks explicitly. Saying your age is just trying to find excuses to justify a sub-par software imo (Not saying this project is sub-par)
Maybe they are rightfully proud that they did this at such a young age?
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> I do actually believe that zero teenagers should make banking apps or run non-profits.
That sounds like a lot of fun and should be a pretty social experience.
Also I'm going to assume his parents are proud, which should put his family at ease.
The parent non-profit organization Hack Club isn't run by teenagers. https://hackclub.com/team/
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There is a vouching system for comments that are flagged.
Click the date on the post, and if you have a button saying "vouch", click that.
It's the lowest cost time to take risks like that, and it's a hell of a lot more constructive than fighting in a world war like 17 y.o men of the past.
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> I adopted the idea of “over the air updates” using Expo’s EAS update service.
Be careful with this. If Apple finds out for instance, your app will still be taken down.
Many developers do this, and it's explicitly allowed under Apple's Developer Agreement (section 3.3.1).
The app store review guidelines (section 2.5.1) seem more narrow, but I think the above is what's enforced.Weird, because Apple took down Fortnite for enabling a direct buy-button (bypassing IAP) after review completed. Just because an offending feature wasn't enabled at the time of review absolutely does not mean you're in the clear to turn it on after the review is complete. Whereas before you'd get the opportunity to fix anything like that during the review process, by sidestepping the review process you'd better be confident you don't ever ship anything that wouldn't pass.
Not that weird, because they were shiving each other in federal court at the time.
I was going to offer a similar, less-absolute warning.
In accounting, finance, M stands for 'mille' aka 'thousand'. So the headline reads $6000/month.
Given how famed HN is for its pedantry I thought you may find this useful as sooner or later someone in your industry might make a judgement on it.
MM is million, BTW.
Hardly. I was an M&A banker for a decade in New York and we used `M` for millions across the board. A few people would use `MM` but on every deck I signed off we used `M` for millions, `B` for billions
Some people do use `MM` but it's far from a standard.
Mostly Europeans.
I think being programmers we'd expect K and M. Save the mm for your financial report.
Humanity has moved on from roman numerals 1000+ years ago. Talk about tech debt.
> In accounting
Only in America.
america is not the entire world
also a simple google search disproves what you are saying. M is correct