Show HN: HCB Mobile – financial app built by 17 y/o, processing $6M/month

[mohamad08]

Hey 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

[KenSF]

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?

[mohamad08]

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.

[sailfast]

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!

[indigodaddy]

The OP title seems a bit misleading notwithstanding this caveat.

[mandeepj]

It’s the same BS that people have at LinkedIn - leading a $250B initiative or increased revenue by $100B

OpenAI’s executive claiming - made one of the top visited websites :-)

[cirrus3]

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

[garyhtou]

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.

[yangikan]

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.

[luke-stanley]

They have this page for reporting: https://github.com/hackclub/hcb/blob/main/SECURITY.md

[galaxy_gas]

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..

[skylurk]

I am surprised you managed to get those entitlements at all!

Did it help to be a non-profit?

[mohamad08]

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.

[VoidWhisperer]

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

[nxor]

It doesn't "seem," it "is."

[necovek]

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).

[riffic]

I really wish something like Hack Club existed while growing up, how empowering! great work.

[rahimnathwani]

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?

[mohamad08]

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.

[whynotmaybe]

Thanks, you just made me realise that I can have OTA update for my app and could deliver more frequently without the play/store hassle!

[brahbrahbat]

This is very helpful to the community. Great work.

[mrb]

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.

[daredoes]

Was just looking at this the other day for personal reasons. Great work!

[miroljub]

Why does it matter how old is the author?

We should judge software by the quality, not by authors age.

[dang]

It's an age-old convention, a way of supporting and encouraging kids, and harmless.

[pinkmuffinere]

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'.

[trollbridge]

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".

[Cyao]

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)

[mohamad08]

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!

[dang]

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

[E-Reverance]

> 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.

[simonw]

The parent non-profit organization Hack Club isn't run by teenagers. https://hackclub.com/team/

[brailsafe]

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.

[LoganDark]

> 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.

[rahimnathwani]

Many developers do this, and it's explicitly allowed under Apple's Developer Agreement (section 3.3.1).

  Interpreted code may be downloaded to an Application but only so long as such code: (a) does not change the primary purpose of the Application by providing features or functionality that are inconsistent with the intended and advertised purpose of the Application (b) does not bypass signing, sandbox, or other security features of the OS; and (c) for Applications distributed on the App Store, does not create a store or storefront for other Applications.

The app store review guidelines (section 2.5.1) seem more narrow, but I think the above is what's enforced.

[DANmode]

I was going to offer a similar, less-absolute warning.

[throwaway5465]

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.

[airstrike]

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.

[esafak]

I think being programmers we'd expect K and M. Save the mm for your financial report.

[enronmusk]

Humanity has moved on from roman numerals 1000+ years ago. Talk about tech debt.

> In accounting

Only in America.

[efilife]

america is not the entire world

also a simple google search disproves what you are saying. M is correct