Hire the Best Backend Rest API Professionals

𝗦𝘂𝗰𝗰𝗲𝘀𝘀𝗳𝘂𝗹 𝗦𝗮𝗮𝗦 𝗽𝗹𝗮𝘁𝗳𝗼𝗿𝗺𝘀, 𝗺𝗮𝗿𝗸𝗲𝘁𝗽𝗹𝗮𝗰𝗲𝘀, 𝗮𝗻𝗱 𝗯𝘂𝘀𝗶𝗻𝗲𝘀𝘀 𝗮𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻𝘀 𝗵𝗮𝘃𝗲 𝗼𝗻𝗲 𝘁𝗵𝗶𝗻𝗴 𝗶𝗻 𝗰𝗼𝗺𝗺𝗼𝗻 - 𝘁𝗵𝗲𝘆 𝗮𝗿𝗲 𝗯𝘂𝗶𝗹𝘁 𝗮𝗿𝗼𝘂𝗻𝗱 𝗿𝗲𝗮𝗹 𝗯𝘂𝘀𝗶𝗻𝗲𝘀𝘀 𝗻𝗲𝗲𝗱𝘀, 𝘂𝘀𝗲𝗿 𝘄𝗼𝗿𝗸𝗳𝗹𝗼𝘄𝘀, 𝗮𝗻𝗱 𝗹𝗼𝗻𝗴-𝘁𝗲𝗿𝗺 𝗴𝗿𝗼𝘄𝘁𝗵. I work with startups, founders, and growing businesses to design and develop software that helps teams operate more efficiently, serve customers better, and scale with confidence. From SaaS products and marketplaces to customer portals, admin dashboards, and custom web applications, I focus on building reliable systems that support day-to-day operations while remaining flexible enough to grow alongside the business. Over the years, I've contributed to products used for customer management, workflow automation, subscriptions, payments, reporting, marketplace operations, and internal process management. 𝗪𝗵𝗮𝘁 𝗜 𝗕𝘂𝗶𝗹𝗱 • SaaS Platforms & Startup MVPs • Marketplaces & Multi-Vendor Platforms • Business Management Systems • Customer & Client Portals • Admin Dashboards & Reporting Systems • Internal Business Applications • Workflow Automation Platforms • Subscription-Based Applications • Multi-Tenant Software Solutions 𝗧𝗲𝗰𝗵𝗻𝗶𝗰𝗮𝗹 𝗘𝘅𝗽𝗲𝗿𝘁𝗶𝘀𝗲 𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱: React, Vue.js, JavaScript, Tailwind CSS, Inertia.js 𝗕𝗮𝗰𝗸𝗲𝗻𝗱 & 𝗦𝘆𝘀𝘁𝗲𝗺𝘀: Custom Business Applications, API Development, Authentication Systems, Third-Party Integrations, Scalable Application Architecture 𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲 & 𝗜𝗻𝗳𝗿𝗮𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲: MySQL, PostgreSQL, Redis, Cloud-Based Deployments 𝗜𝗻𝘁𝗲𝗴𝗿𝗮𝘁𝗶𝗼𝗻𝘀: Stripe, Payment Gateways, CRM Integrations, Email Services, Business APIs 𝗪𝗵𝘆 𝗖𝗹𝗶𝗲𝗻𝘁𝘀 𝗪𝗼𝗿𝗸 𝗪𝗶𝘁𝗵 𝗠𝗲 ✔ Product-focused development approach ✔ Clean, maintainable, and scalable architecture ✔ Strong communication throughout the project ✔ Business-minded technical decision making ✔ Long-term product and growth perspective ✔ Reliable ownership from planning to delivery 𝗜𝗱𝗲𝗮𝗹 𝗣𝗿𝗼𝗷𝗲𝗰𝘁𝘀 • SaaS Platforms & Startup Products • Marketplaces & Multi-Vendor Systems • Customer & Client Portals • Business Management Platforms • Internal Operational Tools • Workflow Automation Solutions 📩 𝗜𝗳 𝘆𝗼𝘂'𝗿𝗲 𝗯𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝗮 𝗦𝗮𝗮𝗦 𝗽𝗹𝗮𝘁𝗳𝗼𝗿𝗺, 𝗺𝗮𝗿𝗸𝗲𝘁𝗽𝗹𝗮𝗰𝗲, 𝗯𝘂𝘀𝗶𝗻𝗲𝘀𝘀 𝘀𝘆𝘀𝘁𝗲𝗺, 𝗼𝗿 𝗰𝘂𝘀𝘁𝗼𝗺 𝘄𝗲𝗯 𝗮𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻, 𝗜'𝗱 𝗯𝗲 𝗵𝗮𝗽𝗽𝘆 𝘁𝗼 𝗱𝗶𝘀𝗰𝘂𝘀𝘀 𝘆𝗼𝘂𝗿 𝗽𝗿𝗼𝗷𝗲𝗰𝘁. 𝗞𝗲𝘆𝘄𝗼𝗿𝗱𝘀: Full Stack Developer, SaaS Developer, SaaS Development, Marketplace Developer, Marketplace Development, Business Systems Development, Custom Web Application Development, Startup MVP Development, Product Development, Platform Development, CRM Development, Client Portal Development, Customer Portal Development, Dashboard Development, Workflow Automation, Business Process Automation, API Development, Custom Software Development, Multi-Tenant SaaS Development, Business Application Development, Scalable Web Applications.

I help established businesses maintain, extend, and stabilize web applications that are already in production without breaking what's working. Most clients who reach out to me are dealing with one of these situations: ✔ A backend system that's grown complex and difficult to extend ✔ An API integration that was done quickly and now needs to be done right ✔ A platform that needs new features without disrupting live operations ✔ A workflow that should be automated but nobody's had time to properly build it If any of these sound familiar, we're probably a good fit. WHAT I WORK ON: ▸ Laravel application development, maintenance & feature extensions ▸ Python backend services & workflow automation ▸ REST API development, third-party integrations & webhook systems ▸ Business systems : ERPs, CRMs, internal tools, admin dashboards ▸ Legacy codebase stabilization, refactoring & modernization ▸ Database architecture, query optimization & performance troubleshooting ▸ AI API integrations (OpenAI, Claude, automation pipelines) ▸ Long-term technical support for live, production platforms HOW I WORK: I treat your system the way it deserves to be treated carefully. Before touching anything, I understand how it's structured, what's already working, and what the business actually needs. I write code that the next engineer can read, not just code that runs today. I'm available for both fixed-scope projects and ongoing engineering support retainers. GOOD FIT IF YOU NEED: ✔ A senior engineer who can own backend systems independently ✔ Long-term collaboration, not a one-off contractor who disappears ✔ Someone who understands business context, not just technical specs ✔ Reliable support for a system that cannot afford downtime or regressions ✔ Technical consultation on architecture decisions, API strategy, or scaling TECH STACK: Laravel / PHP · Python · JavaScript / TypeScript · Vue.js · React REST APIs · MySQL · PostgreSQL · Docker · Linux · Git If your platform is already live and you need an engineer you can trust with it long-term, let's talk!

Founders bring me Supabase backends and AI generated prototypes that work in demos but break under real users. I turn them into production systems with secure multi tenant RLS, working billing, clean migrations, and tests the next developer can trust. Recent client: "Rare at any price point." I specialize in the backend layer most full stack generalists avoid: multi tenant row level security, complex PostGIS schemas, and the production hardening that makes a codebase safe to hand to the next developer. I also run my own SaaS that processes 1M+ property listings nightly, so I build around founder constraints, not just engineering ideals. On my current education platform contract I act as technical lead across a multi contractor team: I make the schema calls, define the API contracts the other developers build against, and review their work before it ships. What I deliver: • Supabase and Postgres architecture. Migrations, triggers, RLS policies, schema cleanup, multi tenant isolation. • Stripe subscriptions. Webhooks, billing state sync, access control tied to subscription status. • Next.js App Router. Server actions, route handlers, API integration, frontend wiring. • AI features that ship. OpenAI and Claude integration, RAG pipelines, evals, guardrails. • PostGIS and spatial data. Location based schemas, GIS queries, Mapbox integration. • Team integration. I slot in alongside your existing developers, automation contractors, and vendors, and I review code as carefully as I write it. • Production handoff. Passing test suites, documented migrations, docs the next dev can follow. Recent Upwork work, all 5.0: • $9,550 fixed price production backend for a workforce analytics SaaS • Municipal GIS platform: 107 row level security policies enforcing per town isolation, Mapbox field mapping, Playwright test coverage. "Honestly one of the best freelancers I've worked with." • 72 table PostGIS schema with RLS on all 72 tables and 189 indexes, delivered ahead of deadline • Backend package: 18 SQL migrations, 14 Edge Functions, 257 passing SQL tests • Education platform, in progress: Stripe billing, Vimeo gated lessons, bulk school enrollment, technical lead across the client's contractor team Top Rated on Upwork. 5.0 across every contract. I'm best for founders who have a real product or a messy build and need it secure, scalable, and ready for customers. I work async by default: GitHub PRs with context, honest timelines, same day responses during working hours. Send a message and I'll reply within a few hours.

I help founders and teams get unstuck when a Laravel, React, or Next.js product needs to move forward without breaking what already works whether that's stabilizing an existing SaaS, extending an admin panel, or picking up a codebase someone else left behind. Top Rated on Upwork, 100% Job Success, $20k+ earned. Where I fit best: ✔ Laravel backend development, API integration, and database design ✔ Stabilizing, auditing, and extending existing SaaS platforms ✔ React / Next.js dashboards, admin panels, and internal tools ✔ Bug fixing, performance work, and ongoing maintenance ✔ Full-stack builds when the project needs both ends done right I'm comfortable working alongside AI-assisted workflows (Claude Code, Cursor). I use them to move faster, but I still read and understand every line that goes into your project before it ships. What clients say: "Kezia produces very high quality work and is committed to successful outcomes." — client review, SaaS code review project "Kezia is genuinely impressive... on time, reliable, very proactive, and goes above and beyond the brief." — client review, ongoing project I ask clarifying questions before I start rather than guess and redo work later, and I give daily progress updates so you're never wondering where things stand. If something outside scope needs fixing, I flag it and ask before touching it, not after. If you have an existing Laravel or React/Next.js project that needs a steady hand, send me the details and I'll tell you honestly how I'd approach it.

Scalable, secure, and designed to grow with your business. Expert Vetted by Upwork with a 100% Job Success Score, I have led the delivery of thousands of full stack projects for clients from early-stage startups to global enterprises including Microsoft and NASA. I lead every engagement directly and handle technical execution end to end. ▸ Expert Vetted - Top 1% of Upwork freelancers ▸ 18 years of full stack delivery ▸ NDA available on all engagements ━━━━━━━━━━━━━━━━━━━━━━ ▸ WORDPRESS & SHOPIFY DEVELOPMENT ━━━━━━━━━━━━━━━━━━━━━━ Custom WordPress themes, Shopify themes, plugins, and apps built from scratch. Custom theme development, child theme development, WordPress multisite, WooCommerce customization, Shopify Plus development, headless Shopify, and Shopify Hydrogen. Deep experience across WordPress and WooCommerce. Certified Shopify Partner. ━━━━━━━━━━━━━━━━━━━━━━ ▸ PHP & LARAVEL DEVELOPMENT ━━━━━━━━━━━━━━━━━━━━━━ Custom PHP development and Laravel applications built for production environments. Multi-tenant SaaS backends, REST API development, GraphQL API development, database architecture, complex business logic, and role-based access control systems. Framework experience across Laravel, CodeIgniter, Symfony, and custom MVC architectures. Third party integrations including payment gateways, CRM systems, ERP platforms, shipping APIs, and accounting software. Custom admin panels, reporting dashboards, and automated workflow systems built to replace manual processes. ━━━━━━━━━━━━━━━━━━━━━━ ▸ MOBILE APP DEVELOPMENT ━━━━━━━━━━━━━━━━━━━━━━ Native and cross-platform iOS and Android applications built in Swift, Kotlin, React Native, and Flutter. Consumer-facing apps, on-demand service platforms, marketplace apps, fintech and payment apps, healthcare and telehealth apps, e-learning apps, real estate apps, and internal business tools. Mobile extensions of existing web platforms, push notification systems, in-app purchase integration, and third party SDK integration. Full UX design, development, QA testing, and App Store and Google Play submission handled end to end from start to finish. ━━━━━━━━━━━━━━━━━━━━━━ ▸ FRONT END & REACT DEVELOPMENT ━━━━━━━━━━━━━━━━━━━━━━ React.js, Next.js, Vue.js, and Angular development. Pixel perfect UI, component libraries, performance optimization, and full stack React applications with Laravel or Node.js backends. ━━━━━━━━━━━━━━━━━━━━━━ ▸ MVP & SAAS DEVELOPMENT ━━━━━━━━━━━━━━━━━━━━━━ Production-ready MVPs from day one — not throwaway prototypes. Multi-tenant SaaS platforms, subscription billing, admin dashboards, role-based access, authentication, and payment integrations. ━━━━━━━━━━━━━━━━━━━━━━ ▸ API & CUSTOM SOFTWARE ━━━━━━━━━━━━━━━━━━━━━━ REST API and GraphQL API development, third party API integrations, webhook implementations, and OAuth authentication systems. Stripe, PayPal, Braintree, and custom payment gateway integrations. CRM integrations including Salesforce, HubSpot, and Zoho. Shipping integrations including FedEx, UPS, and ShipStation. Custom ERP systems covering HRM, CRM, inventory management, sales pipelines, and accounting. ━━━━━━━━━━━━━━━━━━━━━━ ▸ ADDITIONAL SERVICES ━━━━━━━━━━━━━━━━━━━━━━ Custom theme development, child theme development, WordPress multisite, Shopify Plus development, headless Shopify, Shopify Hydrogen, WooCommerce customization, PHP custom development, Laravel API development, REST API development, GraphQL API, React Native mobile app, Flutter mobile app, Kotlin Android development, Swift iOS development, Next.js development, Vue.js development, custom plugin development, payment gateway integration, Stripe integration, PayPal integration, third party API integration, website speed optimization, website migration, ecommerce development, custom web application development. ━━━━━━━━━━━━━━━━━━━━━━ ▸ INDUSTRIES I SERVE ━━━━━━━━━━━━━━━━━━━━━━ Fintech and payment platforms, healthcare and telehealth, EdTech and e-learning, real estate and property management, logistics and fleet management, marketplace and booking platforms, social and community applications, retail and ecommerce, SaaS across every vertical. ━━━━━━━━━━━━━━━━━━━━━━ ▸ RESULTS CLIENTS SEE ━━━━━━━━━━━━━━━━━━━━━━ ▸ Ecommerce stores launching with faster load times and higher conversion rates ▸ SaaS MVPs from scoped brief to live product in 8 to 12 weeks ▸ WordPress and Shopify sites that rank better, load faster, and convert more ▸ Custom software replacing manual processes that previously required dedicated staff ━━━━━━━━━━━━━━━━━━━━━━ ▸ HOW PROJECTS RUN ━━━━━━━━━━━━━━━━━━━━━━ You see the work, test it, and approve it before I move to the next phase. No surprises at invoice time. Direct communication with me throughout. NDA available on all engagements as standard. Message me with a brief description of your project. I will give you a straight answer on the best approach, realistic timeline and what it will cost to build it right.

FastAPI backend engineer and AI agent builder with 5+ years of production experience: Python, n8n, LangChain, RAG, and LLM-powered automation systems that actually ship, not prototypes that break under real use. Recent production work: MarbleBee: AI voice agent platform for a wholesale/DTC business. Twilio for calls, OpenAI for reasoning, RAG-based knowledge retrieval, and ~20 interconnected n8n workflows handling everything from lead classification to Shopify/Etsy product sync and Pinterest publishing. AskVideo: AI video Q&A platform. FastAPI backend, ChromaDB vector search, LangChain orchestration. Users ask questions about video content and get answers with source citations, not guesses. Chatpaper: document Q&A system with hybrid retrieval (dense + BM25 + reciprocal rank fusion), multi-format file support (PDF, Word, Excel), and citation tracking back to source. ALE: enterprise healthcare operations platform. Multi-tenant SaaS, JWT auth, RBAC across three role tiers, RabbitMQ-driven async workers, 35+ REST endpoints, deployed on AWS with CI/CD. What I build: Agentic AI Systems - AI agents with tool-calling, memory, and multi-step reasoning (LangChain, LangGraph) - RAG pipelines with hybrid search (ChromaDB, Pinecone) - Voice and conversational AI with real-time processing Backend & Automation - FastAPI/Django backends: REST APIs, JWT auth, RBAC, async task processing (Celery, RabbitMQ) - n8n workflow automation: webhook-driven integrations, CRM/lead pipelines, third-party API connectors - PostgreSQL/Supabase data models, Docker deployment, AWS infrastructure Core stack: Python · FastAPI · LangChain · LangGraph · OpenAI · Anthropic Claude · n8n · PostgreSQL · Redis · ChromaDB · Docker · AWS · Supabase · Celery · RabbitMQ Anthropic-certified (Claude API, prompt engineering): most AI freelancers on here are OpenAI-only. Also searched as: FastAPI developer, LangChain engineer, LangGraph developer, AI agent developer, n8n developer, RAG developer, agentic AI engineer, Python automation engineer, OpenAI integration developer, AI workflow automation engineer, backend API developer, LLM application developer, Python backend engineer, multi-agent system developer, n8n automation specialist, LangChain RAG developer, FastAPI backend developer, AI agent builder.