SaaS product engineering
Take your product from idea to shipped — or pick up the parts your team can't get to. Full-stack, senior, hands-on, front to back.
Full-stack TypeScript Node · Python
SaaS engineering · Integrations & data · United States
The senior studio that ships your SaaS.
Smiling Boy is a specialist software studio for SaaS founders and teams. We build and ship your product — and the hard parts behind it: integrations, payment gateways, third-party APIs, and the data and systems that keep it running.
- 01 Specialty
- SaaS, integrations & data
- 02 Experience
- Senior engineering · 10+ yrs
- 03 Engagements
- Fixed-scope · Retainer
01 Specialties
Where we go deep.
From shipping the whole product to the integrations and systems behind it — with a proven specialty in the parts where getting it wrong is expensive.
Integrations & payments
Payment gateways (Stripe, Mercado Pago), third-party APIs, webhooks and the glue between systems — built properly, with the edge cases handled.
Stripe Mercado Pago APIs · Webhooks
Data & ML in production
Data pipelines, ML in production, and the data plumbing underneath — built so results are reproducible and easy to trust.
Python ML in prod Data
Fintech & risk systems
Credit-risk, fraud and pricing systems where a wrong number costs real money and audits aren't optional — a proven specialty.
Credit-risk Fraud Pricing
Also: cloud architecture, fractional CTO and general senior engineering — by the hour or on retainer.
02 Selected work
Problems we were brought in to solve.
Three engagements, described without client names — what was broken, what we did, and what changed as a result.
01 Fintech · Risk
Credit-risk & fraud prevention infrastructure
Credit-risk Fraud detection Real-time features
Context
A high-volume fintech platform had gaps in how credit lines were issued and revoked, which left it exposed to fraud.
What we did
We designed and led an end-to-end initiative to revoke compromised credit lines — detection logic, coordination across teams, and a phased rollout that left legitimate customers untouched. We also redesigned the real-time feature computation feeding the risk models.
- 90%
- less credit taken fraudulently, with direct and measurable business impact
- 80%
- faster feature computation, at roughly 300 features a day
02 Data · Real-time analytics
Real-time analytics infrastructure
BigQuery Event-driven GCP · GCS
Context
A global B2B commerce platform had customer data scattered across several internal systems, and slow batch reporting that held up the support team.
What we did
We designed and built a BI service that brought those sources together in BigQuery, plus an event-driven architecture feeding real-time analytics, with date partitioning on GCP/GCS to keep it fast as the data grew.
- 80%
- faster response time from the team to its customers
- 95%
- better query performance and resource usage
03 SaaS · Backend & architecture
B2B prospecting platform for a niche vertical
Backend Integrations Tech lead
Context
An early-stage startup needed to give its audience — independent professionals in a sector still running sales by hand — a simple way to find, enrich and reach prospects without heavy manual research.
What we did
We built the backend behind prospecting: data-enrichment integrations and the outreach campaign flows, plus the rendering layer users actually see. We took technical lead on the architecture — clearer service boundaries, a refactor that cut duplication, and code standards the team kept building on.
- Live
- in production with the first paying customers, validating the model before scaling
- Tech lead
- architecture implemented end to end, with measurable code-quality gains
Client names, logos and identifying details are left out on purpose. We treat our clients' systems as confidential — yours included.
03 Why Smiling Boy
Senior work, without the agency overhead.
We keep engagements small and senior on purpose — so you get the attention of a specialist, not the process of a big shop.
01
Senior engineers who own the outcome
You work with people who have shipped this before — no account managers in the middle, no juniors thrown at your project.
02
We treat your product like our own
We build our own SaaS, so we care about the details that make a product last: reliability, clean data, and the edge cases users actually hit.
03
Honest, no hype
We tell you what we'd do, what we wouldn't, and when a problem isn't worth solving yet. Decisions live in docs and PRs your team can read.
04
Built to ship, and to last
We measure success by what's in production and still running months later — not by hours logged or slides delivered.
Who we work with
Founders & scale-ups
SaaS teams that need senior engineering without a full-time hire — to ship the product, or to take on the integrations, payments and data work behind it.
Established organizations
Health plans, member associations, cooperatives and professional bodies modernizing systems that have been running for years — dated portals, sites that don't work on a phone, integrations nobody has touched in a while. You get a technical counterpart you can talk to directly, not an agency account team.
04 How we work
Three ways to start.
Low commitment first. You never buy the big thing before the small thing proves it out.
Start here
Free product review
A 45-minute look at your product, stack or a specific integration. You leave with three concrete things we'd change — no pitch, no obligation.
Then
Fixed-scope build
A defined problem, a defined deliverable, a clear price. Best for a specific feature, integration or migration.
Ongoing
Senior retainer
A senior engineer on tap, week to week. Best when you need continuity without committing to a full-time hire.
Free product review
Send us your product, stack or a tricky integration. We'll send back 3 things we'd improve.
Free, async, no call required. For SaaS founders and data teams. We usually reply within one business day — no sales sequence, just a senior engineer's read on what you're building.
Start your free review Prefer to write first? The form below works too.
05 Questions
Before you reach out.
How does pricing work?
Three models: a free product review to start, fixed-scope for defined work, or a weekly retainer for ongoing help. We agree on scope and price before anything starts — no surprise invoices.
Who actually does the work?
Senior engineers who own your project end to end. No account managers in the middle, no handoff to juniors, no offshoring layer — that's the point of working with a small, senior studio.
How do contracts and IP work?
Smiling Boy is a US-registered LLC, ready to sign an MSA and invoice properly. You own the work product — IP assigns to you on payment, spelled out in the agreement.
Timezone and communication?
Async-first, written by default — decisions and progress live in docs and PRs your team can read on their schedule. Overlapping hours for the Americas; comfortable working across timezones.
What does a typical engagement look like?
It usually starts with the free review, moves to a small fixed-scope piece to build trust, and grows into a retainer if it's a fit. You're never locked into more than the current step.
06 Contact
Let's talk.
Book a free product review, or send a project brief. Either way, a senior engineer reads it — usually same or next business day.
Response time
Within 1 business day
How
Async-first, written by default
Based in
United States