Principal Architect

Zusei; Singapore; On-site; SGD 180,000 - 260,000; Full time

Benefits offered by this job

Meaningful equity

Job summary

Zusei in Singapore is seeking a Principal Architect to own the technical direction of a live platform where real money moves. You will be the second engineer, own the architecture, and decide how to evolve a pragmatic monolith as the product grows.

Bring a track record of shipping complex systems, learnings from working with a founder-led team, and comfort turning a monolith into modular components when needed. You will help build a small engineering function and set the coding and quality bar.

Qualifications

• Senior technical lead with a real system still running.
• Comfort owning a pragmatic monolith and knowing when to split it.
• Experience on systems where money moves and escrow/custody patterns are relevant.
• You can write code, not only review it.

Responsibilities

• Own the architectural direction of the product.
• Decide when to break up the monolith and how to do it.
• Write and review critical production code paths.
• Help build a small engineering function and set the coding standards.

Skills

System design

Monolith ownership

Coding

Crypto / blockchain

Tools

PHP 8.3

JavaScript

MySQL

nginx

Solidity

Job description

One person wrote all of Zusei. The consumer app, the merchant console, the marketing site, and the two smart contracts on Base. Every line, in eleven months, by a founder who came out of seven years in marketing and taught himself to ship because waiting for a technical co-founder was going to cost him the idea.

It works, it is live, and real money moves through it. It is also exactly what you would expect from that story. There are places where speed won and structure lost, and we know where most of them are because we went looking rather than waiting to find out.

You would be the second engineer. Not a hire slotted under a VP Engineering into a system somebody else already decided. The architecture is genuinely yours to set.

What you would actually own

One person wrote all of Zusei. The consumer app, the merchant console, the marketing site, and the two smart contracts on Base. Every line, in eleven months, by a founder who came out of seven years in marketing and taught himself to ship because waiting for a technical co-founder was going to cost him the idea.

It works, it is live, and real money moves through it. It is also exactly what you would expect from that story. There are places where speed won and structure lost, and we know where most of them are because we went looking rather than waiting to find out.

You would be the second engineer. Not a hire slotted under a VP Engineering into a system somebody else already decided. The architecture is genuinely yours to set.

What you would actually own

Take the single key out of the middle. Every mint, burn, transfer and escrow operation is currently signed by one private key held in the server environment. One key, one process, all value. It works at our size and it does not survive growth, and it is the first thing any external reviewer would raise. Replacing it, without breaking a live product or a user's balance, is a real piece of engineering and it is yours.

Move settlement to stablecoins. Rewards are denominated in our own points token today. A bar owner does not want a points balance, she wants to put dollars behind a campaign and watch dollars leave only when someone walks in. We are migrating the escrow to USDC. That work is scoped and committed to.

Make verification hold up against people who try. Our whole argument is that we can prove a person was physically somewhere. The server already re-checks merchant ownership, event validity and pass uniqueness, and refuses to trust device location. It will need to be better than that, because the moment rewards are worth farming, someone will try. Our founder spent seven years watching people game incentive systems at crypto exchanges, so you will not have to explain why this matters.

Take it from one city to many. Everything today assumes Singapore. The second market is what decides whether this is a local product or a category. That is a data model question, a deployment question and an operations question, and right now nobody has answered any of them.

Bring the discipline. Tests, CI, review, staging. There is a set of home grown static checkers that catch real bugs, and honestly they punch above their weight, but they are not a test suite. You would decide what good looks like here and then make it normal.

The stack, stated plainly so you can rule us out fast

PHP 8.3 with no framework. PDO against MySQL 8. Vanilla JavaScript, no build step. nginx on a single EC2 instance. Background work runs on cron. The onchain layer is Solidity on Base, driven by a small Node bridge using ethers.

If that list makes you wince, we would rather you stopped reading here than joined and spent six months trying to turn it into something else. The monolith is a deliberate choice for a product this size maintained by a team this size, and we would want you to argue about when that stops being true, not to assume it already has.

If that list makes you think "I could do a lot with this", we should talk.

What we are looking for

• You have been the senior technical person on something real, and you can describe a system you designed that is still running and why it was built that way
• You are comfortable owning a pragmatic monolith and know when to break one up, which is later than most people think
• You have worked on something where correctness mattered because money moved
• You can write the code, not only review it. For a while you will be half the engineering team

Useful but not required: smart contract experience, particularly escrow or custody patterns. Anti fraud or abuse prevention work. Anything involving physical world verification, hardware, logistics, ticketing or access control. Having been early at a startup and seen what actually breaks at 10x.

Genuinely not required: a computer science degree, crypto true belief, or experience in our exact stack. Our founder had none of the three.

What this is not

It is not a role where you inherit a team. There is no team yet. You would help build one.

It is not a greenfield rewrite. There are real users and real merchants with real money in escrow. You would be changing the engine while it runs, which is harder and more interesting than starting over.

It is not a title in search of a job. Principal Architect here means you own the technical direction and you are accountable for it.

Compensation

• Negotiable, and meaningful equity is on the table. We would rather have the conversation properly with a person we want than post a band that is wrong for most people who read it.