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# Full-Stack Developer — B2B SaaS for Water Well Management (Implementation on Existing Architecture) ## About us We are a Brazilian water well drilling and maintenance company digitizing our entire operation — and building it as a multi-tenant SaaS from day one, with the goal of later offering the platform to other companies in our industry. We operate in Brasília, Brazil (UTC-3). ## What we are building A B2B operations platform that sits at the intersection of three product categories: 1. **Field service management** (think ServiceTitan / Jobber, but for water wells): customers, work orders, field crews, equipment, field bulletins, a future offline-first mobile app for technicians. 2. **Contract & progress-measurement billing** (think Procore's commercial flow): versioned proposals, contracts with line items, amendments, field work measured against contract items, approval workflow, invoicing, Brazilian tax documents (NFS-e) and payment reconciliation. 3. **Water telemetry** (think HydroVu / AQUARIUS): continuous time series from field probes (water level, flow, conductivity, temperature), quality flags, provenance, alert rules. Around this core: a CRM with customer dossiers and conversation history, document management on Google Drive (metadata in Postgres, binaries in Drive), Telegram bots (customer-facing for billing/status, internal for alerts and queries), payment collection through the **Asaas** gateway (Pix, boleto — webhooks), and later an MCP server so AI agents can query the platform under strict policies, plus RPA automation for Brazilian water-rights agencies. ## What already exists (read carefully — this defines the job) We have a **versioned architecture and data-model baseline (v3.0.0 handoff package)** produced and validated statically. It contains: - PostgreSQL/PostGIS **multi-tenant relational model**: ~147 tables across 19 domain schemas (platform, IAM, registry, CRM, commercial, operations, hydrogeology, observations, measurement, finance, post-construction, documents, integration, audit, MCP); - **12 migrations** with tenant isolation enforced by Row-Level Security **and** composite foreign keys `(tenant_id, id)` on every tenant-scoped reference; - seeds, SQL tests, invariants and **state machines** documented per domain; - initial **OpenAPI 3.1 contract** (16 operations) and an **MCP tool catalog** with access policies; - inbox/outbox event pattern with idempotency, audit and data-classification policies; - Google Drive folder templates and a dry-run provisioning script; - ADRs recording the closed architectural decisions. **This engagement is about implementing the application layer on top of this baseline — NOT redesigning the data model.** Proposals to "start simple with Firebase/MongoDB" or rebuild the schema are an automatic no. Evolving the model through new migrations, with justification, is expected and welcome. ## Scope of the first engagement (paid pilot, fixed scope) 1. **Database bring-up:** run all migrations on a real PostgreSQL/PostGIS instance (Docker locally, Cloud SQL for dev), fix any issues via *new* migrations, get the provided SQL tests passing (RLS isolation, composite FKs, business sequences). 2. **Project foundation:** monorepo setup, CI (GitHub Actions), dev environment, secret management, linting/test conventions. 3. **One thin vertical slice, end-to-end, with tests:** authentication → tenant resolution → customer dossier creation → an authorized "work order status" query (respecting RLS + permission matrix) → audit log of the disclosure → exposure through the OpenAPI endpoints. 4. **Deployment of this slice to GCP Cloud Run** (API + database connectivity + Secret Manager), with basic observability (structured logs, error reporting). **Acceptance criteria:** migrations apply cleanly from zero; SQL tests pass; the vertical slice works through the API with automated tests; RLS proven by a cross-tenant access test; deployed and reachable in a dev environment; README updated so another developer can onboard in under one hour. Estimated effort: [YOUR ESTIMATE — e.g., 3–5 weeks]. Budget for the pilot: [YOUR BUDGET / or "please propose"]. ## Roadmap after the pilot (awarded based on pilot performance) Phase 2 — Asaas integration (webhook inbox, charge mirroring, reconciliation with receipts) · Phase 3 — internal Telegram bot (alerts, queries) · Phase 4 — water-rights/licensing entities with expiry alerts · Phase 5 — telemetry ingestion (device registry, raw payload inbox, alert engine) · Phase 6 — offline-first field app · Phase 7 — customer Telegram bot + reports (PDF) · Phase 8 — MCP server · Phase 9 — RPA for agency portals. This is a long-term, multi-phase project for the right person or small team. ## Fixed tech stack - **Database:** PostgreSQL 16 + PostGIS (Cloud SQL in production) - **Backend:** Node.js + TypeScript (NestJS preferred; we will discuss module layout mirroring the domain schemas) - **Frontend:** React + TypeScript ([login to view URL]), shadcn/ui, Tailwind; Tremor-style dashboards; design north star: Linear — clean, fast, information-dense B2B admin - **Infra:** GCP — Cloud Run (services + jobs), Pub/Sub, Cloud Scheduler, Secret Manager, Cloud SQL - **Integrations:** Telegram Bot API, Asaas (payments, webhooks), Google Drive API (service account), later MCP - **Non-negotiable principles:** all access through the API/application services (bots and integrations never touch the database directly); tenant comes from the authenticated context, never from the request body; webhook processing is idempotent (inbox pattern); domain events via outbox; AI tools never execute arbitrary SQL. ## Must-have skills - Advanced PostgreSQL in production: Row-Level Security, composite keys, migration discipline, query planning - Real multi-tenant SaaS experience (you can explain how you prevented cross-tenant leaks) - TypeScript across the stack; NestJS or comparable modular backend architecture - Webhook/event-driven integration patterns with idempotency - Automated testing culture (unit + integration against a real Postgres) ## Nice-to-have PostGIS · GCP (Cloud Run, Pub/Sub) · Telegram bots · payment gateways · IoT/time-series ingestion · field-service or construction-tech domain · offline-first mobile (React Native/Expo) · experience working from an OpenAPI-first contract. ## Language requirement (critical filter) The database schema, domain vocabulary, documentation and product UI are in **Brazilian Portuguese** (`[login to view URL]`, `medicao.boletim_medicao`, …). You must be comfortable working in a Portuguese-language codebase. **Brazilian / Portuguese-speaking developers are a strong plus.** Communication with me can be in Portuguese or English. ## Working model Milestone-based contract through this platform · code in our GitHub organization from day one · pull-request reviews (I review with AI assistance and an architecture checklist) · short async updates 2–3×/week, one weekly call · preference for ≥4h overlap with UTC-3. ## Selection process 1. Short reply describing your most similar multi-tenant/Postgres project and what you'd watch out for in ours. 2. Shortlisted candidates receive the full handoff package (docs + migrations) under the platform's confidentiality terms and return: (a) questions/risks you identified, (b) your plan and estimate for the pilot. The quality of your questions matters as much as the estimate. 3. Interview (technical, 45 min) and pilot award. ## What we provide The complete v3.0.0 handoff package (docs, ADRs, migrations, seeds, SQL tests, OpenAPI, MCP catalog, Drive templates), a macro capability map of the whole platform, GCP project access, Asaas sandbox, and a responsive product owner who knows the domain deeply and answers fast.
Project ID: 40613628
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204 freelancers are bidding on average $3,781 USD for this job

Hi there, We understand you're seeking a robust SaaS platform for hydrogeology that offers real-time monitoring of water levels, quality, and groundwater flow, along with data analysis, visualization, and automated report generation. With our expertise in SaaS development, custom PHP solutions, and experience in data visualization using AngularJS, we're confident in delivering a comprehensive platform. Our team has worked on similar projects, such as developing a learning platform with real-time data tracking and a custom CRM system with automated reporting. One question: Have you considered integrating any specific hydrogeological models or APIs for enhanced data accuracy and forecasting capabilities? Feel free to message us to discuss the details! — Webbook Studio
$3,150 USD in 30 days
9.3
9.3

Combining SaaS expertise with hydrogeology knowledge for a real-time monitoring platform is crucial. With experience in both areas, I'm well-equipped to exceed expectations. To ensure success, I seek insights on scalability projections and security requirements. By prioritizing user experience, performance, and scalability, the platform can adapt to future needs. Collaboration with your team will guarantee a tailored solution, fostering a lasting partnership. Together, we can innovate and set new standards in hydrogeological monitoring.
$4,500 USD in 5 days
8.9
8.9

With the unique combination of almost two decades worth of industry experience and cutting-edge innovation, CnELIndia is excellently poised to deliver your Comprehensive Hydrogeology SaaS project. Our deep understanding of web and app development technologies such as PHP - the lynchpin of PostgreSQL, and WordPress - which could be invaluable in building this multi-tenant SaaS platform, gives us an unequivocal edge over other candidates. In choosing CnELIndia, you can be confident that you're opting for a partner committed to bringing your unique vision to life. We are excited by the challenge and possibility of your B2B SaaS product and look forward to contributing our skills towards its manifestation and eventual expansion into other companies in the industry. Let’s collaborate on transforming your Brazilian water-drilling company's operations into a multitenant SaaS system that'll revolutionize the industry!
$4,000 USD in 15 days
9.1
9.1

As a leader in the global marketplace, our team at Yasir's Software has a proven track record in SaaS development and creating comprehensive web applications. We recognize the importance of real-time monitoring, accurate data analysis and visualization tools, as well as efficient report generation - all of which aligns perfectly with your project goals. In addition to our strong SaaS and software development background, we also boast a deep understanding of hydrogeology, making us uniquely qualified to build a platform tailored specifically to your needs. Our wealth of experience in handling real-time data monitoring systems combined with our expertise in data visualization and analysis ensures that your desired functionalities are robustly implemented. At Yasir's Software, we value customer satisfaction and focus on building long-lasting relationships. We believe in continuously adding value to our clients' businesses by leveraging the latest technologies. Let us work together to turn your comprehensive hydrogeology SaaS dream into a reality. Your project is not just another job for us, it's an opportunity for us to demonstrate our skills and passion in transforming complex ideas into elegant solutions. Don't just take my word for it, let us show you - pick us, you won't be disappointed!
$3,000 USD in 40 days
8.6
8.6

Hello, I reviewed your project and I'd be happy to help build your Hydrogeology SaaS platform. I have experience developing custom SaaS applications with user management, subscription systems, interactive dashboards, GIS/map integrations, data visualization, reporting, and role-based access. I'll focus on building a scalable, secure, and user-friendly platform that is easy to maintain and can grow as your business evolves. I'm available to discuss your requirements in more detail and can start immediately. Thanks, Sujay
$3,000 USD in 30 days
8.5
8.5

Good to see this project, I will build your hydrogeology SaaS platform with three core modules: real-time water level monitoring (surface, groundwater, reservoir), water quality dashboards, and groundwater flow visualization. Automated PDF/CSV reports will generate on the schedule you define. On a recent environmental monitoring platform, structuring the ingestion pipeline around MQTT kept sensor data latency under two seconds, even with hundreds of field devices reporting simultaneously. I will architect yours the same way. Questions: 1) Are you integrating with existing field sensors or loggers, and if so, what protocols do they use (Modbus, SDI-12, API)? 2) Will the platform need multi-tenant access so different organizations or field teams each see only their own sites? Send me a message and we can go over the details. Best regards, Kamran
$3,447 USD in 30 days
8.6
8.6

As an AI-powered digital solutions provider, I see tremendous potential in your project for synergy between our skill sets and your desired outcomes. Web Nautical's portfolio boasts over 100 successful projects across multiple domains with a strong focus on intelligent systems, software development, and web/mobile applications. Our team comprises experts in AI development and database management, both of which are critical to delivering the comprehensive Hydrogeology SaaS you envision. Our proficiency in PostgreSQL and PostGIS aligns seamlessly with your existing data model and multi-tenant relational structure. Taking responsibility for bringing-up the database, we'll draw on our considerable experience running complex migrations on real-time instances to ensure your SQL tests pass without issue. Lastly, let me emphasize that our approach emphasizes building upon the existing framework rather than overhauling it entirely. Understanding the significance of your v3.0.0 handoff package for established business processes, we will ensure seamless integration of new features while respecting existing structures. By selecting Web Nautical, you are choosing a capable partner that can contribute value right from database migration to secure DevOps deployment—ultimately revolutionizing water well management for your company in Brasília and beyond.
$5,000 USD in 35 days
8.5
8.5

Hi, I’ve read your requirements carefully, including the v3.0.0 handoff package, and I completely understand that this engagement is about implementing the application layer on top of your existing PostgreSQL/PostGIS architecture—not redesigning it. I can confidently help you build this. My team has already developed similar multi-tenant SaaS platforms with strict tenant isolation, PostgreSQL, complex relational schemas, event-driven workflows, webhook integrations, RBAC, audit logging, and NestJS/React applications. We have hands-on experience with RLS, composite keys, Cloud Run deployments, CI/CD pipelines, and production-grade API development. A few questions: Is authentication already implemented (JWT/OIDC), or should it be included as part of the pilot? Will the OpenAPI specification remain the source of truth, or are endpoint changes expected during implementation? I’m confident I can deliver a clean, production-ready pilot and would be happy to discuss the timeline and estimation in detail. Thanks Rahul
$5,000 USD in 60 days
8.6
8.6

With my profound experience in Full-Stack Development spanning over 12+ years, I possess the necessary skills to bring your vision of a comprehensive B2B SaaS platform for water well management to life. Despite the complex nature of this project, I am particularly skilled at working with existing architectures and identifying precise areas where improvements can be introduced without compromising what was already in place. Just as you've mentioned, my approach is rooted in not just writing code but producing clean, scalable and secure solutions that yield optimal results both now and in the long-run. One aspect that makes me a valuable asset is my in-depth knowledge of both back-end and front-end development technologies including Node.js, React, PHP, Laravel, Python, WordPress, Shopify, Wix and Square. Moreover, my extensive experience with databases-in particular PostgreSQL and PostGIS-coupled with an impressive understanding of API integrations; provide me with an inherent understanding of your core requirements; allowing me to seamlessly implement your existing multi-tenant relational model.
$3,000 USD in 7 days
8.1
8.1

⭐⭐⭐⭐⭐ Full-Stack Developer for B2B SaaS Water Well Management Solutions ❇️ Hi My Friend, I hope you're doing well. I've reviewed your project needs and understand you're looking for a Full-Stack Developer for your B2B SaaS platform. Look no further; Zohaib is here to assist you! My team has completed over 50 similar projects in SaaS development. I will implement the application layer on your existing architecture using best practices to ensure smooth functionality and performance. ➡️ Why Me? I can easily handle your Full-Stack Development needs as I have 5 years of experience in PostgreSQL, Node.js, and TypeScript. My expertise includes multi-tenant architecture, API design, and automated testing. I also have a strong grip on deployment strategies and event-driven integrations. ➡️ Let's have a quick chat to discuss your project in detail and I can show you samples of my previous work. I look forward to discussing this with you in our chat. ➡️ Skills & Experience: ✅ PostgreSQL ✅ Node.js ✅ TypeScript ✅ NestJS ✅ React ✅ GCP ✅ API Development ✅ Event-Driven Architecture ✅ Automated Testing ✅ Docker ✅ CI/CD (GitHub Actions) ✅ Webhooks Waiting for your response! Best Regards, Zohaib
$3,400 USD in 2 days
8.0
8.0

Hi, I checked your "Comprehensive Hydrogeology SaaS Development" project and it looks like understanding the existing workflow will be important before making any changes. I've worked on similar PHP projects involving php, website design, software architecture, software development, angularjs, data visualization, data analysis, saas and prefer delivering work in small milestones so everything stays easy to review and adjust if needed. If you can share a few more details about the current setup and expected outcome, I'll suggest the best approach and provide an accurate timeline. ⭐ 5.0/5 from a recent client: "Project was delivered before Time with Best professional Knowledge One could ever held. Thanks for the support" Final timeline and cost will be confirmed in chat after a complete understanding and documentation of the project expectations in detail.
$3,000 USD in 59 days
7.7
7.7

Hi, this reads like a domain-heavy SaaS rather than a simple website, and the success factor will be getting the data model and workflow boundaries right before building UI around them. The real engineering risk is not PHP or AngularJS itself; it is translating hydrogeology logic into a system that preserves calculation traceability, visualization accuracy, and maintainable multi-user workflows. I usually structure platforms like this around a clean separation between domain data, processing rules, and presentation so the product can evolve without rewriting core logic. The closest relevant work here is Custom Feature Development & Integration, where I stepped into an existing product, reviewed architecture, and implemented coordinated UI, database, and core-function changes. HubSpot CRM Implementation & Interactive Senior Living Website is also relevant for building a data-driven platform with searchable interfaces and production workflows. I would approach this by defining the canonical entities, processing steps, and reporting outputs first, then separating ingestion, analysis, and visualization layers. That keeps scientific logic testable and reduces rework when reporting requirements change. These systems need to be designed for long-term production use, not just a first demo. If useful, I can sketch the initial application architecture and first-release workflow boundaries from the current requirements. Thanks, Hercules
$4,000 USD in 7 days
7.6
7.6

With over a decade of experience and more than 300 successful projects under our belt, Walking Dreamz Technologies is your ideal partner for this comprehensive hydrogeology SaaS development initiative. Led by me, Kishore, we've consistently delivered high-quality web, mobile, and software solutions that focus on clean code, predictable delivery, and excellent communication. Our core skill set lines up perfectly with the diverse requirements of your project; Custom MERN web apps (dashboards, SaaS, admin panels), WordPress & WooCommerce (custom themes, redesigns) and AI & automation applications. Our proficiency in these areas ensures that we can flawlessly execute your vision for the B2B operations platform you envision while ensuring future extensibility and scalability. Moreover, we have a deep appreciation for the existing architecture and data-model baseline that you've created, v3.0.0 handoff package to be precise. We understand the importance of building upon this solid foundation rather than ripping everything apart and starting from scratch. With us, you can expect a disciplined approach to staging new migrations as needed and of course, all evolutions will come with thorough justifications to maintain the integrity of your platform's vision. Let's put our capabilities to work for you and create a solution that is not only stable but easy to extend tomorrow.
$3,500 USD in 24 days
7.7
7.7

You're building Comprehensive Hydrogeology SaaS Development, where the real delivery risk is usually in the workflow details, not just the feature list. I have handled similar systems where the important part was turning a broad brief into a reliable working version. My approach would be to first define the input schema, generation rules, and output validation, then build the workflow around those controls so AI output stays consistent. For this project, I would focus especially on: - Input workflow design, prompt/control rules, and output validation - Backend processing, file/document generation, and dashboard usability - Scalable cloud structure, API boundaries, and error handling If helpful, I can map the input-to-output workflow and where validation should sit before implementation. Best, Dr. Syafiq
$4,000 USD in 21 days
7.5
7.5

Hi, I’ve read your hydrogeology SaaS brief carefully, and I’m confident I can build a robust PHP-based platform for real-time monitoring, analysis, and automated reporting. This is the kind of structured Software Development and Software Architecture work I handle with a focus on scalable dashboards, clean data pipelines, and reliable performance. I can develop the SaaS system to manage live water-level and quality inputs, build Data Analysis and visualization modules, and automate report generation in a way that is practical for ongoing field use. My approach will focus on a secure backend, clear reporting workflows, and an interface that makes complex monitoring data easy to interpret. I can outline the architecture and delivery milestones right away, with a first planning phase starting immediately. Would you like the real-time monitoring to ingest sensor data through APIs, CSV uploads, or both? Best regards, KANIKA
$4,200 USD in 45 days
7.1
7.1

Hello, I am very interested in developing the Comprehensive Hydrogeology SaaS platform you described. With my expertise in Website Design, PHP, Software Development, AngularJS, and Software Architecture, I am confident in creating a robust platform that meets your requirements. I understand the need for real-time monitoring of water levels, water quality, and groundwater flow, along with features like data analysis tools and automated report generation. - MY WORK STATS: ✨ https://www.freelancer.com/u/XanvraTECH I would love to discuss this project further and explore how I can bring your vision to life. Best regards, Warda Haider
$3,000 USD in 16 days
6.8
6.8

Hello! As per your project post, you are looking to build an Hydrogeology SaaS Platform for real time monitoring and analysis of surface water, groundwater, reservoirs, water quality, and groundwater flow. The platform will help users monitor live environmental data, analyze trends through clear visualizations, and generate automated reports for better decision making. My approach would focus on creating an intuitive monitoring dashboard where users can view real time readings, explore historical trends, compare data points, and generate professional reports. The platform will be structured to support multiple monitoring locations and data sources while remaining scalable for future hydrogeological analysis and reporting requirements. I specialize in SaaS platforms, real time dashboards, data visualization, analytics systems, automated reporting, API integrations, and scalable web applications. My focus will be on making complex environmental data easy to understand while providing a reliable foundation for future expansion. Let's connect to discuss your monitoring requirements and turn your hydrogeology platform into a practical, scalable solution. Best regards, Nikita Gupta
$3,000 USD in 28 days
7.0
7.0

For your Comprehensive Hydrogeology SaaS Development project, look no further than Web Crest. We are a seasoned software development company, proficient in constructing tailored solutions for unique industries. Our expertise stretches beyond SaaS platforms and software design. Throughout years of service to various sectors, including hydrogeology, we have acquired an in-depth understanding of industry requirements and specialized skills in handling crucial data on water levels, quality, flow, and more. What sets us apart is our capability to seamlessly integrate real-time monitoring capabilities into your system. With proficiency in advanced technologies like AngularJS and PHP, we create user-friendly interfaces that provide valuable insights from collected data. Moreover, our adeptness in data visualization and analysis ensures that you receive meaningful, digestible results to drive informed decisions. Better yet, we can automate report generation for your convenience. Beyond delivering the technical aspects, our approach is also business-focused. We understand the long-term necessities of scalable and secure digital products and will ensure your platform remains future-ready. Additionally, our commitment extends post-development with long-term technical support. Let's us help bring your vision for a comprehensive hydrogeology SaaS solution to life; together we can build something outstanding!
$3,000 USD in 7 days
6.7
6.7

Hi there, Hope you are doing well I'd love to help implement your Hydrogeology Multi-Tenant SaaS Platform. My team has extensive experience building enterprise-grade SaaS applications with complex PostgreSQL architectures, secure multi-tenant systems, and scalable cloud deployments. We understand that this engagement is focused on implementing the application layer on your existing architecture—not redesigning the database. We fully support working within your existing GitHub repository, following your architecture decisions, migration strategy, OpenAPI contracts, and long-term roadmap. We look forward to discussing the pilot scope, identifying potential risks, and delivering a scalable foundation for future development phases. Looking forward to working with you. Thanks & Regards, Dheeraj K.
$3,000 USD in 25 days
7.0
7.0

As an experienced and versatile full stack developer fluent in Node.js and TypeScript, I am well-equipped to handle the multi-faceted nature of your Comprehensive Hydrogeology SaaS Development project. Specifically, my deep understanding of the entire stack, from data analysis and visualization to architecture design dovetails perfectly with your firm's need to leverage existing assets without re-engineering database schemas. In addition, my extensive experience working with PostgreSQL, including advanced skills in Row-Level Security and composite FKs makes me perfect for the job. Having successfully created SaaS solutions for a wide range of clients in the past, I understand the importance of not only delivering on immediate tasks but also designing with future development phases in mind. This is especially crucial given the unique nature of each well drilling/maintenance company's workflow. My deftness with webhooks and idempotency patterns are clear plus points when it comes to developing work order management systems like yours.
$4,000 USD in 7 days
6.0
6.0

Brasília, Brazil
Member since Jul 29, 2026
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