We are seeking a skilled Frontend Developer to join our dynamic team and play a critical role in the planning and estimation phases of frontend development projects. This position offers a unique opportunity to combine your strong technical frontend skills with project planning expertise to help shape the direction and scope of upcoming development initiatives. You will collaborate closely with cross-functional teams including product managers, designers, backend developers, and QA engineers to ensure that frontend deliverables are accurately scoped, efficiently executed, and aligned with business goals. The ideal candidate is not only proficient in modern frontend technologies but also experienced in anticipating development challenges, estimating timelines, and contributing to the overall project roadmap. If you are passionate about building high-quality user interfaces and enjoy engaging in strategic discussions about project feasibility and resource allocation, this role is perfect for you. Join us to help drive impactful frontend solutions while ensuring realistic planning and effective use of technical resources throughout the development lifecycle. Your responsibilities for this role will be to: - Collaborate with product managers and designers to gather and analyze frontend requirements and translate them into technical estimates. - Participate actively in project planning meetings to provide accurate time and resource estimations for frontend tasks. - Develop, review, and maintain scalable, responsive, and high-quality frontend code using modern frameworks such as React, Angular, or Vue.js. - Work closely with backend developers to ensure seamless integration and consistent user experience across platforms. - Identify potential development risks and propose mitigation strategies during the estimation and planning phases. - Continuously improve frontend architecture and workflows for enhanced maintainability and performance. - Provide technical guidance and mentorship to junior frontend developers to uphold coding standards and best practices.

We're building the next platform for SBL Nova, a company that already monitors tens of billions of dollars in securities collateral for banks, broker-dealers, and RIAs. The next version of that platform needs to handle collateral that lvives on-chain — tokenized real-world assets, stablecoin settlement, and AI agents that can act on risk in real time instead of just flagging it. We're not hiring someone to build this from a spec doc or a Figma file. We already built a working prototype ourselves — a real Next.js 16 / React 19 / TypeScript app with actual client-side state, a working wallet connect/disconnect flow, a live approve/deny queue for agent actions, working search and filtering, and a functioning notifications inbox. It runs with zero API keys or backend — clone it, npm install, npm run dev, and you can click through the whole thing in under a minute. What it doesn't have yet — and what we need you for — is everything below the surface: - Wiring up a real ERC-4337 smart wallet (ZeroDev, Alchemy Account Kit, or Safe) behind our existing wallet context, replacing our mocked address with a live, session-key-scoped account - Building a real policy engine for our "agentic ops" screen — the UI for approving/denying agent actions already exists, it just needs actual agents behind it reading live testnet events - Pulling real on-chain data into our collateral registry and activity feed via an indexer (The Graph) or an RPC provider (Alchemy/Infura) Standing up and auditing the actual smart contracts our security registry currently mocks (think Slither, Foundry, Echidna) - Replacing our AI risk-scoring mocks with a real model — even a solid heuristic or scikit-learn baseline on real testnet transactions would be a big step up - Adding real authentication, role-based access, and a persistence layer (API + database) so this isn't just in-memory React state anymore What we're looking for: - Someone comfortable across the full stack — Next.js/React/TypeScript on the frontend, and confident building real backend services and APIs - Solid hands-on experience with EVM chains (we're targeting Ethereum, Arbitrum, and Polygon zkEVM) and account abstraction / smart wallets - Experience writing or auditing Solidity contracts, or working closely with a security process (Slither/Foundry/Echidna/Certora are all fair game) - Some real AI/ML experience — not "I used ChatGPT," but building and shipping actual models or pipelines, even simple ones - Someone who can look at existing code, understand the shape of a half-built system, and just start extending it — not someone who needs a fully specced ticket for every step How we'll work together: We'll give you the full prototype repo up front so you can see exactly what's already built and exactly where the mocked pieces are. From there we'd want to move in scoped chunks — smart wallet integration first, then the policy engine, then real data feeds — rather than one giant undefined project. Ongoing engagement if it's a good fit, with clear milestones so both sides know where things stand. Looking forward to hearing from you!

PLEASE NOTE: ALL DIRECT CALLS AND EMAILS WILL BE BLOCKED, AND SENDERS WILL BE DISMISSED FROM CONSIDERATION, EVEN ON UPWORK. WE WILL NOT WORK WITH ANYONE WHO CONTACTS US OUTSIDE OF UPWORK. ZERO EXCEPTIONS. We are seeking a full-stack developer for both the ongoing maintenance of current products as well as the development of new products. We are a sports media company that creates applications that help fans be more effective when it comes to attending live sporting events. EXISTING PRODUCT DEVELOPMENT: Our first product launched two months ago: calendar.thestadiuminsiders.com, a custom calendar which incorporates team sports calendars (NFL, NBA, NHL, MLB, etc.) plus concerts/special events into a single view for each city. This required the integration of calendars from multiple sources in multiple formats, consolidated into a single view. Lots of moving pieces. The calendar has been developed, successfully launched, and is very stable. But there is ongoing maintenance to do, as well as continued enhancements to make. Our calendar was built in React, Next.js, and Firebase (this was not an AI developed product: it was built the old fashioned way). It also incorporates ICS feed parsing, which is critical. You need to understand these elements, as well as complex data architectures and data management. (Our advice: please don't approach your proposal by telling us about all of the pitfalls and traps waiting for us. We've had great developers and product managers working extremely hard to build a great product, and we haven't overlooked the complexities and nuances. We need someone to take a really well-built product and build on top of it, not tell us how they're going to come in and save it from assured collapse. We're happy to hear that you understand some of those traps and nuances and complexities. Just please don't assume we haven't thought of them. Better to focus on why your experience is a good fit, rather than explaining coding to us). NEW PRODUCT DEVELOPMENT: Separate from the above product, we have a pipeline of products that are on deck that are being developed via vibe coding (specifically in Lovable), but we need a developer who can push them the last 10 yards before launch. Porting these projects from Lovable into Claude is completely fine (we know Claude is the stronger dev platform), but our front-end team is working in Lovable because it is an easier interface. But I expect we will move the projects over to Claude once we have the right person in place to assist with that. General Requirements: --NextJS --React --Firebase Functions and Firestore --NoSQL design --ICS calendar formats --CSV uploading --Vercel --Vibe coding (specifically taking products built with Lovable and making them production-ready) An understanding of sports is helpful, as it makes it easier to understand the relationship between teams, venues, leagues, and cities. You don't need in-depth specific understanding of stats or players or such, but an understanding of sports leagues will make it easier to understand the tasks at hand. In terms of approach, we will first want to make a bunch of quick fixes/improvements to the calendar app, followed by two more substantive upgrades. After that we will turn our attention to new products. Please note: 1) Every AI response is exactly the same (literally). You're not setting yourself apart at all, and we can't tell if you have any idea what you're talking about or what our project requires. Also ... our AI filter catches 99% of AI submissions. Use AI at your own risk. 2) We vet every candidate before speaking to them. If your location, experience, education, and skills don't match your other public profiles, we will not be able to engage with you. If Upwork says you're in Miami, and LinkedIn says you're in New York, that will be a red flag. 3) Bids above our stated range will be declined. Sorry for the laundry list: recruiting has become very difficult in the age of AI, so we just want to advise everyone upfront on our process. Thanks -- we appreciate your interest, and we look forward to finding someone great. This is a fun product and an interesting company, especially for someone who likes sports.

SEEKING HIGHLY MOTIVATED US DEVELOPERS / AMERICAN CITIZENS ONLY! Full-Stack and Mobile Developers needed for Back-end, Front-end, and Mobile development. We are seeking AMERICAN developers who have strong skills in PHP, Python, Java, Javascript, React, Vue.js, Typescript and Flutter. Both Web application and Mobile application development work available. Experience with data scraping / data analysis is a plus. Must have excellent command of Linux, SQL, and Git. No slackers, no agencies, no middlemen, no "teams". Please be the person you claim to be, and please be the individual who proposes to do the work. Serious candidates only. *NO VIBE-CODERS* *NO WINDOWS USERS* Please be a Mac or Linux user for your personal machine. You must be able to connect to our Linux servers and ready to hit the ground running with no issues. You must be motivated, enthusiastic, and ready to get to work. Must be willing to have brief 20-minute VIDEO interview. Be ready to bring your A-game! THIS JOB IS AVAILABLE FOR U.S. CITIZENS ONLY.

Given everything you've described, I wouldn't just hire another "web developer." I'd hire a **Senior Full-Stack Engineer** with experience taking over existing projects. That's a completely different skillset. Here's an Upwork posting I'd use: --- # Senior Full-Stack Developer (Next.js + Django + Stripe) – Take Over Existing Project We are looking for a **highly experienced senior full-stack developer** to take over an existing web application that was started by another developer. This is **not** a project for someone who needs hand-holding or is learning these technologies. We need someone who can quickly understand an existing codebase, identify what's complete, what's broken, what's missing, and efficiently finish the product. ## Tech Stack Must have professional experience with: * Next.js * React * TypeScript * Django * Django REST Framework * PostgreSQL * AWS * Stripe (REQUIRED) * Git/GitHub ## Stripe Experience (Required) You **must** have significant experience implementing Stripe, including: * Hosted Checkout * Payment Elements * Webhooks * Subscription billing * Customer portal * Refunds * Payment state management * Stripe Dashboard * Production deployments If Stripe is not something you've implemented multiple times, this is not the right project. ## Project The application is an online travel service with: * Multi-step customer application * Customer dashboard * Admin dashboard * User authentication * Payment processing * Email workflows * PDF generation * AWS deployment A previous developer has completed part of the project, but we need someone who can independently evaluate the codebase and finish the application correctly. ## Responsibilities Your responsibilities will include: * Review the existing codebase * Audit completed work against the original project scope * Identify missing functionality * Fix existing issues * Complete unfinished features * Improve code quality where necessary * Deploy production-ready code * Work directly with us during testing and revisions ## Important Our previous developer required a significant amount of frontend guidance and revisions. As a result, our team ended up recreating many HTML pages and UI components ourselves. We're looking for someone who can: * Take ownership * Ask questions before building when requirements are unclear * Build polished, modern interfaces without constant direction * Deliver production-quality work the first time Communication is extremely important. We'd much rather answer questions upfront than spend time rebuilding work later. ## To Apply Please include: 1. Links to **3 projects** you've personally built using Next.js and Django. 2. Describe your experience with **Stripe**, including subscriptions, webhooks, and payment flows. 3. Have you ever taken over another developer's unfinished project? Tell us about it. 4. How would you approach auditing an unfamiliar codebase before writing new code? 5. Your GitHub (if available). 6. Your hourly rate. 7. Your availability. ## Bonus Experience * AWS deployment * Sentry * Docker * CI/CD * PDF generation * Email automation * Travel platforms * Headless browser automation * Playwright

We are looking for an exceptional Full-Stack Engineer who enjoys solving challenging technical problems across the entire technology stack—from modern user interfaces to scalable backend services, cloud infrastructure, and AI-assisted software development. This engagement begins as a contract position with strong potential to become a long-term member of our engineering team. What You’ll Be Building This is not a typical CRUD application. You will be working on a technically sophisticated SaaS platform involving: • AI-powered healthcare analytics • Large-scale clinical and pharmacy datasets • Complex SQL and data processing pipelines • Interactive analytics dashboards • Modern React-based user interfaces • High-performance backend APIs • Enterprise system integrations • Cloud-native infrastructure • AI-assisted software engineering workflows If you enjoy designing scalable systems, solving complex technical challenges, and building products that have real-world impact, we’d love to hear from you. Responsibilities You will work closely with our founders and engineering team to: • Design and develop new product features from frontend through backend. • Build intuitive, responsive, and high-performance web applications. • Design scalable backend services and REST/GraphQL APIs. • Design and optimize relational databases and complex SQL queries. • Improve application performance, scalability, and reliability. • Build integrations with external healthcare systems and third-party services. • Participate in architectural and technology decisions. • Debug and resolve complex production issues. • Write clean, maintainable, well-tested production code. • Contribute to engineering best practices and continuous improvement. Required Technical Skills Frontend • React • TypeScript • Modern JavaScript • Responsive web development • Component-based architecture • State management Backend • Expert-level Python • Node.js • FastAPI, Django, or Flask • REST APIs • GraphQL • Authentication & Authorization • Asynchronous programming Databases Strong experience with relational databases including: • PostgreSQL • MySQL • SQL query optimization • Indexing • Performance tuning • Data modeling • Database design Cloud & Infrastructure • Docker • Kubernetes • AWS • CI/CD pipelines • Git Modern AI-Assisted Development We strongly prefer engineers who actively leverage modern AI-assisted software development tools to improve productivity while maintaining exceptional engineering quality. We view AI as a productivity multiplier—not a replacement for software engineering expertise. The ideal candidate understands how to use AI effectively while applying sound engineering judgment, architecture, debugging skills, and rigorous code review. What We’re Looking For We’re looking for engineers who: • Think like software architects—not just programmers. • Can independently solve complex technical problems. • Take ownership of their work. • Write elegant, maintainable, and well-tested code. • Have excellent debugging and troubleshooting skills. • Make thoughtful architectural decisions. • Learn quickly and continuously improve. • Communicate clearly and professionally. • Enjoy working in a fast-moving startup environment. We value engineering excellence, problem-solving ability, and sound technical judgment far more than years of experience alone. Nice to Have Experience with one or more of the following is a plus: • Large-scale analytics platforms • Event-driven architectures • Redis • Elasticsearch • Message queues • Data engineering • Performance optimization • DevOps Required Application Questions To help us identify the strongest candidates, please answer the following questions in your proposal. 1. Describe the most technically challenging application you have built. Please include: • Overall system architecture • Your specific role • Technologies used • The biggest technical challenge • How you solved it • What you would do differently today 2. Which area of software engineering do you enjoy the most, and why? Examples: • System architecture • Backend development • Frontend development • Databases • Performance optimization • Infrastructure • Debugging • AI applications

Summary: We are building Sphere Inc., an AI-powered SaaS platform focused on the real estate industry. The product is currently in the MVP stage, and we are looking for a strong full-stack developer who can help us build, refine, and launch the first working version. The platform is designed to help real estate businesses automate daily operations, improve decision-making, and use AI agents to support workflows such as property management, lead handling, deal analysis, document processing, reporting, and business automation. This is not a basic website project. We are building a real SaaS product with a modern frontend, reliable backend, AI-powered workflows, and scalable AWS infrastructure. Current Project Status: The product vision and core direction are already defined. We are currently shaping the MVP workflows, user experience, and technical structure. At this stage, our main need is execution. We need someone who can help turn the concept into a working MVP that can be tested with real users. Some workflows are still being refined, so we are looking for a developer who can contribute both technically and practically — not just write code from fixed tickets. Current Progress & Bottlenecks We have a clear direction, but need support with - Structuring the MVP architecture - Building the frontend and backend features - Designing practical AI agent workflows - Connecting AI features with real estate data and user actions - Setting up AWS infrastructure for development and deployment - Creating a clean experience for non-technical business users - Prioritizing the most important MVP features The main bottleneck right now is moving from concept/prototype stage into a stable, usable product. We are looking for someone who has experience with - Building SaaS products from MVP to production - Full-stack development with Python, Node.js, JavaScript, and TypeScript - Frontend development using React, Next.js, or similar frameworks - Backend APIs, database design, authentication, and user roles - AI agents, LLM integrations, workflow automation, or RAG - AWS deployment, storage, monitoring, and security - Real estate platforms, CRMs, property data, document workflows, reporting, or automation tools - Writing clean, maintainable, and scalable code Tech Stack: Python, Node.js, JavaScript/TypeScript, React or Next.js, PostgreSQL, AWS, REST APIs, and AI/LLM tools such as OpenAI, Anthropic, AWS Bedrock, LangChain, LangGraph, or similar frameworks. Responsibilities: - Build frontend and backend features for the MVP - Design and implement AI-powered workflows and agent features - Connect APIs, databases, authentication, and user roles - Set up or improve AWS infrastructure - Help prioritize features and identify technical risks - Communicate progress clearly and regularly Some Knowledge That Is a Plus: - Real estate CRM, property management, brokerage, acquisitions, or leasing platform experience - AWS Bedrock, LangChain, LangGraph, or vector databases - Multi-tenant SaaS architecture - Stripe or subscription billing - DevOps, Docker, CI/CD, and testing - Analytics dashboards, reporting tools, or document automation The ideal candidate is a reliable full-stack developer who can work independently, understand the product vision, ask smart questions, and help us make practical technical decisions during the MVP stage. We need someone who is comfortable in an early-stage environment and can help turn a clear idea into a working SaaS product for real estate users. Please include: 1. Your GitHub, portfolio, or examples of previous work 2. A brief description of your related SaaS experience 3. Examples of AI agent, AI automation, or LLM-powered products you have built 4. Your AWS experience 5. Any real estate platform, CRM, data, or automation experience 6. Your availability and preferred working style We are looking for someone who can help us build the MVP now and potentially continue with us as the platform grows.

We're looking for a senior full-stack developer with a strong security background to extend and harden a large, mature application. You'll navigate an existing codebase with real history and real constraints, implement security controls, optimize performance, and keep the system scalable and reliable. You should have deep, self-earned coding fundamentals and know how to use AI as a force multiplier. This is not a role for developers who depend on AI to write code they couldn't write themselves. You should be able to reason through a large legacy codebase unaided — your engineering foundation is what separates AI producing noise from AI producing shippable work. About the Role The stack is TypeScript end to end: a Next.js frontend and AWS-backed services. AI tooling is a deliberate part of the workflow — generating implementation plans, stress-testing those plans against our architecture and business requirements, reviewing generated code for correctness, and shipping with confidence. When AI hits the limits of a complex legacy system, and it will, you're the one who knows how to guide it through. What You'll Do Own the full lifecycle of AI-assisted development: draft plans, pressure-test them against real architectural constraints, and validate that generated code is production-worthy Ensure solutions respect existing codebase structure, clean architecture principles, and layered design patterns Validate that all code — generated or hand-written — ships with appropriate unit and end-to-end tests and thoughtful edge case coverage Apply and enforce security best practices aligned to the NIST Special Publication series on federal security controls: access control, audit logging, system integrity, and secure configuration management across frontend and backend Act as a rapid-response resource for user-facing issues — diagnose, prototype, and deploy fixes fast when production is on the line What We're Looking For Five or more years of proven TypeScript development, with a body of work predating widespread AI coding tools — you know the language, not just the prompts Deep proficiency in React and Next.js Strong working knowledge of AWS (Lambda, SQS, DynamoDB, IAM, and similar) The ability to critically read generated code and catch architectural drift, security gaps, and subtle logic errors the model won't flag itself Familiarity with the NIST federal security control framework or comparable standards, and the judgment to translate controls into practical engineering decisions Comfort using AI tools (Claude Code, Copilot, and similar) as a development partner, with the depth to steer them in unfamiliar or complex codebases Strong debugging instincts and the ability to move fast under pressure without cutting corners on security or quality Bachelor's degree in Computer Science or a related field Nice to Have Mobile platform experience (iOS/Android), infrastructure-as-code, or CI/CD pipeline work. Familiarity with FedRAMP, SOC Type II, or other compliance regimes that map to the NIST control catalog.

I am seeking a skilled React Native/Expo developer to complete an existing sports notification app. The project involves working with existing code to enhance features and ensure smooth functionality. The ideal candidate should have experience in mobile app development and be able to deliver high-quality results efficiently.

Hi, I have spent $243,000 on UpWork and I am easy to work with because I am a consultant myself. Check out how other people rate me on this platform. I have been building a react native app for about a year now and I need an expert react native developer to do a code review. I was thinking you could take 10 hours to do a deep dive on my app and write up all the issues you see so I can fix them. I developed everything myself but I need another set of eyes on this. Backend is supabase.