Full-stack software that ships and stays up.
I'm Mervin Magpantay, a Senior Software Engineer with 7+ years building enterprise systems — Java & Spring Boot backends, Angular & TypeScript frontends, and SaaS products of my own like proofito.
Java · Spring Boot · TypeScript · Angular · REST APIs · Microservices · SQL · Docker
Years of software engineering
Production releases shipped
Deployment success rate
Faster incident turnaround, sustained
Track record from 7+ years shipping enterprise software — the same rigor I bring to every project.
Services
What I can build for you
Backend to frontend to production — pick the slice you need, or hand me the whole thing.
Backend Development
Spring Boot services built for production — REST APIs, microservices, and JPA persistence that hold up under real load.
Frontend Development
Responsive, maintainable interfaces in Angular and TypeScript — from enterprise dashboards to marketing sites.
API Design & Integration
Clean REST contracts, webhook handlers, and third-party integrations — documented, tested, and versioned.
Databases
Schema design, tuning, and migrations across Oracle, MS SQL Server, and MySQL — the DB analysis I did for years, now for you.
DevOps & Delivery
Dockerized builds, CI/CD pipelines, and disciplined releases — 3,100+ production releases shipped at a 99% success rate.
SaaS Product Builds
End-to-end product development: I take an idea from architecture to paying users. proofito — my document-rendering API — is the proof.
Selected Work
Products I've designed, built & shipped
Real software in production — not mockups. Each one I own end to end: architecture, code, deployment, and the 2 a.m. pages.
Work 01
proofito — document rendering API
One API that turns any URL or HTML into screenshots, PDFs, and OG social images. I designed, built, and run it solo on Cloudflare Workers with real Chromium — from the render engine to billing.
Live in production · free tier with no credit card · self-serve API keys
Real Chromium rendering
screenshots, PDFs, OG images — one endpoint
Content-hashed render cache
X-Cache HIT/MISS, served from R2
Self-serve API keys
Google login mints revocable sk_live_ keys
Per-key usage metering
tracked in D1, billed via Paddle
Work 02
Astraea Tech — one login, every product
The platform behind my products: a single Google sign-on that works across every Astraea property, with subscriptions and API keys kept per product. proofito plugs into it today; future products will too.
Shared auth, per-product billing — the boring infrastructure, done once and done right
Single sign-on
one Google login across *.astraeatech.dev
Scoped sessions
parent-domain cookies, revocable anytime
Per-product everything
subscriptions and API keys stay per product
Work 03
This portfolio — Next.js + Three.js
The site you're reading: a fully static Next.js build with a Three.js node-graph hero, scroll choreography, and animated metrics — designed and built end to end.
Static export · deploys to the edge · this page is the demo
3D hero
rotating node graph with mouse parallax
Static prerender
zero servers, ships anywhere
Motion system
scroll reveals, counters, tilt cards
Why Me
Hire senior-level delivery, without the agency overhead.
Most freelancers sell you a slice — frontend only, backend only, “deployment is someone else's problem”. I spent 7+ years owning full slices of software that clients depend on around the clock: analysis, design, code, tests, docs, and production support. That's the standard your project will be held to.
New to freelancing. Not to engineering.
My Upwork profile is new — my standards aren't. Rated “Exceeds Expectations” six review cycles in a row as a software engineer. Early clients get senior-engineer quality at new-freelancer rates.
Enterprise QA discipline
3,100+ production releases shipped at a 99% success rate for enterprise clients. Your project gets the same testing rigor.
Built for the 2 a.m. scenario
Error handling, logging, and monitoring from day one — not bolted on after the first silent failure.
End-to-end ownership
Backend, frontend, database, and deployment — one person accountable for the whole slice, no handoff gaps.
Documentation & true handover
Video walkthroughs, runbooks and clean credentials handling. You own everything I build — no lock-in, ever.
Process
A clear project, from brief to handover.
I use Upwork for project conversations, agreements, reviews and payments. You have one place to see what we agreed, what comes next and what needs your approval.
- 1
Start with a short conversation
Share your brief on Upwork
Create a client account or sign in, then open my profile to message me or invite me to your project. We clarify fit in Upwork Messages or an Upwork call before you commit.
Your partSend your goal, must-have features, target date, rough budget and a reference if you have one.
What you getA fit check and a clear next step.
- 2
Know what you are buying
Agree the scope and fund the work
We record the deliverables, exclusions, acceptance checks, revision rounds, deadline and fixed price in Upwork. Work starts after the contract is active, funding is in place and required materials are ready.
Your partReview the written scope and fund the agreed milestone or available Catalog order on Upwork.
What you getA written agreement, funded work and a content/access checklist.
- 3
Visible progress, clear feedback
Try the work as it takes shape
I share working previews, progress and test results in Upwork. You try the agreed flows and send one combined feedback list. Changes beyond scope get a separate written agreement before I build them.
Your partTry the preview and collect feedback from the person who can approve it.
What you getReviewable progress and a record of decisions.
- 4
Your acceptance matters
Review the delivery and approve launch
I submit the agreed deliverables through Upwork's official review flow. Review them against our checklist, request in-scope changes or approve in the contract. A build goes live when you authorize launch.
Your partUse Upwork's Request Changes or approval control before the review deadline shown in your contract.
What you getA checked delivery and, where included, an approved release.
- 5
You can keep running it
Receive the handover and support
You receive the agreed files, source for code work, a walkthrough and operating notes. Builds and code repairs include 14 days of in-scope defect fixes from the agreed handover date. New features are quoted separately.
Your partSave your files, confirm access to your accounts and send any support findings through Upwork.
What you getA usable handover, clear ownership and defined support.
Why create an Upwork client account?
One project record
Keep the brief, messages, agreed scope, files, approvals and payments in one workroom.
Funded work, with review
For fixed-price work, funding is deposited before work begins. You review the submission and can request changes before approving it.
A route to resolve problems
Eligible contracts have Upwork payment protection and dispute assistance, subject to its rules and deadlines.
New client guide: signup, review deadlines and fees
Choose the client / hiring option on Upwork's signup page and complete its setup. Then open my profile to message or invite me. Already have an account? Sign in and use your client profile.
For standard fixed-price milestones and Project Catalog submissions, Upwork normally gives you 14 days to approve or request changes; no action can release payment automatically. Follow the deadline shown in your contract.
For Project Catalog, submit mandatory requirements within 48 hours of purchase. Its delivery countdown starts when those requirements are received. Ask me to confirm fit before ordering an available listing.
Protection depends on Upwork's terms and eligibility; it is not an unconditional refund guarantee. Upwork's client fees and applicable taxes are separate from my quote and shown in its checkout.
The 14-day Upwork review window is separate from my 14-day defect support. A diagnosis-only project delivers its agreed report, without a code fix or launch.
Toolbox
The whole stack, one engineer.
Contact
Let's build something solid.
A new product, a system that needs rescue, or extra senior hands on your team — share a short brief on Upwork. We agree the scope, price and next steps there before work starts.
Already on Upwork? Open my profile to message or invite me. New here? Choose the client / hiring option when signing up, then return to my profile.
Designed and built by Mervin Magpantay with Claude — this site is itself a sample of the work.
© 2026 Mervin Magpantay · Batangas, Philippines · GMT+8, overlaps US & EU hours · Next.js + Three.js + Tailwind