Finta (YC W23)

Most of my summer went into these six things.

I built Finta's Slash and Rho bank integrations from scratch, covering OAuth connect, account, transaction and treasury sync, multi-account support and reconnect alerts, all behind feature flags. Later on I added reconnect logging across all four bank providers that never writes a token or raw payload to the logs. Finta announced the Slash partnership once it went live.

The bug I remember most was Slash sync quietly stopping after 100 rows, so accounts looked synced when they weren't. I fixed the pagination, added a regression test and backfilled the accounts that got affected.

These are two filters customers kept asking for, one by card and one by who spent the money, and they work across Mercury, Rho, Slash and Plaid banks like Amex, Chase and Citi. When a Slash card deploy got rolled back I reconciled the production schema and got both filters working again. Here are the launch demos Finta put out:

Ask Finta is the in-app assistant. I gave it tools that can search, edit and split transactions and create rules, with permission and company checks on every call, and built a Respan eval suite to make sure it behaves before anything goes live.

Founders already live in Slack, so that's where Finta meets them: transaction alerts and monthly summaries land in a channel they pick, and Ask Finta posts its updates there too. I built out the Slack side of that, with a settings flow that walks you through connecting your workspace and picking a channel, a welcome DM once you're connected, and delivery that only counts a message as sent once Slack confirms it, so nothing quietly goes missing.

I built the referral program end to end, from the invite in settings and matching at signup to applying the Stripe coupon on upgrade, the claim link and the accept and reject emails, and shipped it behind a feature flag.

Every Stripe event, whether it's a charge, a refund, a dispute or a payout, has to get booked to the right category in a customer's books. The trouble was that webhooks, admin tools and cleanup jobs each had their own copy of those rules, so the same event could get booked differently depending on which path touched it. I moved the rules into one routing policy that all three paths call, then worked through the edge cases one by one: credits, cancellations, disputes, reversals, sales tax, financing and missing balance transactions. Along the way I also made the multi-page catch-up jobs resumable and capped admin imports at 100 transactions.

Finta was my first startup job and my first summer living in San Francisco, working on a small team where the code I wrote went in front of real customers within days, and a few things from that stayed with me.

It was the most I've grown in a few months, and I'm grateful to the Finta team for trusting an intern with work that customers actually relied on.