Senior Backend Engineer – Large-Scale Transaction Systems - 26/01/2026 08:16 EST -- 2

@AwaisChaudhry

Hi there, I'm Muhammad Awais, a senior backend engineer who thrives on scale, concurrency, and reliability. I can design distributed automation and simulation systems to orchestrate thousands of browser/API workflows for procurement scenarios, with robust session state, retries, and partial successes. I have hands-on with Python (async), Go, Node.js, Kafka/Redis, and Playwright. My approach: event-driven architecture, scalable orchestration with queues, realistic user modeling, strong observability, and validated load testing. MVP in ~4 weeks; full stabilization in ~12 weeks; 4-week sprint cadence. Deliverables: architecture docs, production-grade code, tests, dashboards. What is your top priority for the first milestone: throughput, reliability, or realistic behavior modeling? Key questions to align early: - Throughput targets and latency goals. - Platforms to simulate and anti-bot constraints. - Browser automation vs API-driven flows preference. - Queues/messaging choice and infra constraints. - How session state is defined, stored, and expired. - Observability expectations: logs, metrics, traces, dashboards. - Security/compliance: data handling, secrets, access controls. - Deployment/CI/CD/rollout plan (canary/feature flags). - Cloud budget constraints and cost vs scale. What is your top priority for the first milestone: throughput, reliability, or realistic behavior modeling? Best regards,

@shrec

I can contribute as a senior, hands-on systems engineer with strong experience designing distributed, high-concurrency automation and simulation platforms. I’ve built resilient systems that orchestrate thousands of concurrent workflows, manage state at scale, and model realistic user behavior with robust retry, observability, and failure-handling strategies. I’m comfortable owning architectural decisions around reliability, latency, and cost, and implementing them in production-grade Python, Go, or Node.js. This kind of complex, non-CRUD, system-level engineering is exactly the space I specialize in.

@LiveExperts

Hello, With a pioneering background in diverse backend systems, I, Mirza Muhammad and my team at Live Experts®, LLC are uniquely equipped to tackle the complex challenges of your project. Our main strength lies in building scalable, concurrent, and resilient architectures- exactly what you need for high-scale automation and simulation systems. Over our 5+ years of experience, we have mastered key languages like Python and have strong hands-on experience with async processing, queues/workers (like SQS, Kafka, Redis), and state management at scale. What sets us apart is our ability to think outside the box. We’ve been involved in projects related to trading systems, fraud detection systems, and gaming systems- all requiring a thorough understanding of scale, concurrency, reliability and robust modeling. We also have extensive knowledge of behavioral modeling and user generation which are critical for your project. I must emphasize that unlike other applicants who might just scrape the surface of the project requirements، we genuinely understand how crucial this senior engineering role is for your organization and vow to deliver production-grade architectural solutions. As specialists in transforming ideas into reality, we pledge to provide a scalable system that handles the intricacies of large-scale transactions adeptly – all within your prescribed timeframe. Reach out today to see how we can bring our skills and shared dedication Thanks!

@ZohaibRoy

⭐⭐⭐⭐⭐ Build High-Scale Automation Systems for Digital Procurement Workflows ❇️ Hi My Friend, I hope you're doing well. I've reviewed your project requirements and see you are looking for a senior systems engineer. You don't need to look any further; Zohaib is here to assist you! My team has completed 50+ similar projects for high-scale automation systems. I will design and implement distributed architectures, manage workflows, and ensure reliability while keeping within your budget. ➡️ Why Me? I can easily handle your project as I have over 5 years of experience in systems engineering, focusing on distributed systems, Python, and automation. My expertise includes async processing, state management, and browser automation frameworks. Additionally, I have a strong grip on handling high concurrency and debugging under real-world conditions. ➡️ Let's have a quick chat to discuss your project in detail. I’d love to show you samples of my previous work and how I can add value to your project. Looking forward to our conversation. ➡️ Skills & Experience: ✅ Python (async) ✅ Go ✅ Node.js ✅ Distributed Systems ✅ Automation Frameworks ✅ Async Processing ✅ Queue Management ✅ Session State Management ✅ Logging & Metrics ✅ Error Tracking ✅ Behavioral Modeling ✅ Debugging Skills Waiting for your response! Best Regards, Zohaib

@irsolutions

With over 10 years of experience in web and mobile development, specializing in backend engineering for large-scale transaction systems, I understand the key challenge of building distributed, resilient systems for high-scale automation. Your project requires expertise in designing and implementing complex architectures that orchestrate thousands of concurrent workflows with realistic user behavior patterns. My experience aligns perfectly with your requirements, having successfully delivered similar projects in the past. I have a strong background in building high-concurrency, distributed systems using Python, Go, and Node.js. My portfolio includes projects in fintech and blockchain domains, demonstrating my ability to handle complex systems with precision and efficiency. If you're looking for a seasoned backend engineer with a proven track record in system design and implementation, I am ready to take on this challenge. Let's discuss how I can contribute to your project and help you achieve your goals. Feel free to reach out to me for further details on my expertise and relevant project references.

@corpmember29

I HAVE BUILT LARGE-SCALE DISTRIBUTED AUTOMATION SYSTEMS HANDLING THOUSANDS OF CONCURRENT USERS IN MARKETPLACE AND TRADING SIMULATIONS. Proposal: System Architecture: Design and implement resilient, distributed automation/simulation frameworks modeling human-like workflows. Concurrency & Scale: Orchestrate thousands of concurrent browser/API-based actors with async processing, queues (SQS/Kafka/Redis), and robust state management. Behavioral Modeling: Simulate realistic timing, sequencing, and variability; handle retries, partial failures, and observability (logging, metrics, error tracking). Technologies: Python (async)/Go/Node.js, Playwright/Puppeteer, Postgres/Redis, Docker/Kubernetes. Deliverables: Production-grade distributed system; documented architecture; monitoring dashboards; tested simulation workflows. Experience: 5+ years senior backend/systems engineering; strong background in marketplaces, high-concurrency systems, behavioral simulation. Engagement: Remote, full-time contract, initial 3–6 months, start ASAP. I can provide references to similar large-scale automation platforms and GitHub samples upon request. Ready to start immediately and deliver a robust, scalable solution.

@tangramua

Dear ,   We carefully studied the description of your project and we can confirm that we understand your needs and are also interested in your project. Our team has the necessary resources to start your project as soon as possible and complete it in a very short time.   We are 25 years in this business and our technical specialists have strong experience in Python, Node.js, Redis, Backend Development, Automation, API Development, API Integration, Distributed Systems and other technologies relevant to your project.   Please, review our profile https://www.freelancer.com/u/tangramua where you can find detailed information about our company, our portfolio, and the client's recent reviews.   Please contact us via Freelancer Chat to discuss your project in details.    Best regards, Sales department Tangram Canada Inc.     

@nikhilgarg96

With my extensive 5+ years of senior backend/systems engineering experience combined with a strong command over a variety of languages, including Python (async), Go, Node.js, I believe I am an excellent candidate for your project. I have hands-on experience with high-concurrency distributed systems, async processing of queues/workers (e.g. SQS, Kafka, Redis), and state management at scale, which are all key components needed for this role. In addition to my technical expertise, I also bring a unique perspective due to my background and familiarity with behavioral modeling or synthetic user generation. My experience in trading systems and anti-cheat systems has required me to build large scale transaction systems while modeling realistic user behavior patterns, something that perfectly aligns with this project. I take pride in my strong opinions on system design and my ability to defend them. This position requires someone capable of making key architectural decisions and evaluating trade-offs efficiently. If you're looking for an engaged professional with the skills and experiences needed for a successful completion of your project, look no further than me! Let’s connect and create impactful solutions together! With Regards!

@hireageek

Hi there, I am a top California freelancer with extensive experience in backend engineering, specializing in designing high-scale transaction systems. I have successfully completed numerous projects, earning five-star reviews for my delivery and expertise. Given your need for a senior engineer to build resilient and distributed systems for transaction-heavy workflows, I am confident in my ability to meet your requirements. With over five years of hands-on experience in Python and distributed systems, I have a strong background in managing concurrency and implementing observability metrics. I have designed solutions that emulate realistic user behavior, which I believe aligns perfectly with your project's goals. I am eager to collaborate on architectural decisions that balance latency, reliability, and scalability. Let’s connect to discuss your project further and identify the best approach moving forward. What specific challenges do you foresee in achieving the desired concurrency and reliability in your systems?

@mubeenm5026

Having closely studied the project description, I'm very excited about the prospect of joining your team as a senior backend engineer. With over 5 years of experience in backend/systems engineering, I have developed a knack for solving hard problems that arise when working with scale, concurrency, reliability, and system behavior modeling; which aligns perfectly with the core challenges of this project. My extensive hands-on experience with Python (async), Go and Node.js serves as an ideal platform for designing and implementing distributed automation/simulation architectures, orchestrating workflows, managing state and failures effectively. So far, I have mainly worked in AdTech/Fraud systems similar to this project domain. In addition, I am well-versed with several browser automation frameworks such as Playwright and Puppeteer along with API-driven workflows. I understand and value the importance of tracking data effectively to ensure proper implementation which is why I have also mastered logging, metrics & error tracking tools. My expertise is also reflected in my understanding and application of Async processing, Queues/workers (e.g. SQS, Kafka and Redis). Your project requires someone with strong debugging and problem-solving skills under real-world constraints which form a significant part of my programming ability. Moreover, the fact that I'm comfortable working remotely would be an added convenience for both of us.

@Dimitarg1

Senior backend/systems engineer with 8+ years building high-concurrency, distributed platforms and automation-heavy backends. I’ve designed and implemented systems that coordinate thousands of concurrent workers, handle async job orchestration, retries, partial failures, and stateful workflows using combinations of queues, event-driven processing, and horizontal scaling. Recent work includes high-throughput automation services, distributed job schedulers, and simulation-style systems for load testing, marketplaces, and messaging/notification pipelines. Relevant experience: Distributed worker architectures using Go & Node.js Async processing, message queues (Redis, RabbitMQ, Kafka-style patterns) Session/state management at scale Browser & API automation using Playwright / Puppeteer Observability: structured logging, metrics, tracing, alerting Designing realistic behavior models (timing jitter, probabilistic actions, sequencing) Preferred Stack: Go or Node.js for core services, Redis/Kafka/SQS for queues, Postgres for state, Docker, AWS. I’m comfortable making architecture trade-offs around reliability vs latency and cost vs scale, and enjoy solving exactly these kinds of hard systems problems.

@Mahihassi

As a veteran in building robust systems for complex and high-concurrency applications, I am confident that I can meet the challenges of your project. I have more than five years of experience in senior backend/systems engineering with a strong command over Python (async), Go, and Node.js, which are considered essential to build distributed automation/simulation architectures like the one your project demands. Having worked on projects involving browser automation frameworks such as Playwright and API-driven workflows simulation, I possess a profound understanding of state management at scale, async processing, queues/workers (e.g., SQS, Kafka, Redis). My hands-on experience will prove instrumental in managing session state, retries, failures, and partial success scenarios, ensuring you get a reliable system that can orchestrate thousands of concurrent browser or API-based workflows. Notably, my background in areas such as trading systems and AdTech/Fraud systems lends valuable insights into this project's dynamics. My familiarity with behavioral modeling and strong opinions on system design only adds to my compatibility with your requirements.

@softsolution2000

I specialize in Python, Node.js, Redis, Backend Development, and Automation, making me an ideal fit for the "Senior Backend Engineer – Large-Scale Transaction Systems" project. My extensive experience in building high-concurrency systems aligns perfectly with the requirements. Budget flexibility is not an issue as my focus is on delivering quality work within your parameters. Please review my 15-year-old profile to see my track record. Let's discuss the project details. I am eager to showcase my commitment by starting work immediately. Excited to hear from you soon.

@Julian29

Hello, HAVE HANDS-ON EXPERIENCE WITH SUCH PROJECT **** You may track the project’s progress in the tracker. I am committed to 40 hours weekly **** I have 9+ years of proven experience in high-concurrency, distributed backend systems and confidently understand your need for a production-grade simulation and automation platform for transaction-heavy workflows. The goal is to design and build a resilient, scalable system that orchestrates thousands of concurrent, human-like actors across browser/API workflows with robust state management and observability. Core features -->> distributed orchestration + worker queues (SQS/Kafka/Redis) -->> async browser automation (Playwright/Puppeteer) and API workflows -->> realistic behavioral modeling & variability -->> session/state management with retries & partial success handling -->> metrics, logging, error tracking. My approach uses clean architecture, event-driven design, fault-tolerant workers, and strong observability to ensure reliability at scale, while balancing latency, cost, and throughput. I will provide 2 years of free ongoing support, full documentation, and collaborative architecture reviews to ensure the system is production-ready and extendable. Let’s connect in chat to align on your target scale, platforms, and key success metrics so I can propose a detailed implementation plan and timeline. Thanks & regards Julian

@Feriver

Hi, I am a senior backend and systems engineer with extensive experience designing and operating large-scale, transaction-heavy automation platforms. My focus is on distributed architectures that reliably orchestrate thousands of concurrent actors while preserving realistic behavior, fault tolerance, and operational visibility. I have built high-concurrency systems using Python (async), Go, and Node.js, leveraging queues, worker pools, and stateful orchestration layers to manage complex workflows at scale. My work includes simulation engines that model human-like interaction through timing variance, stochastic behavior, session lifecycles, retries, and partial-success handling without brittle automation patterns. I am comfortable owning architecture decisions end-to-end, balancing latency, cost, and reliability while ensuring systems degrade gracefully under failure. I have delivered production-grade platforms with robust observability, including structured logging, metrics, and trace-level diagnostics. My background aligns strongly with trading systems, fraud-resistant automation, and load simulation environments where correctness, resilience, and behavioral fidelity are critical. I bring strong system design opinions, hands-on execution, and a focus on building systems that remain stable under real-world constraints. Preferred stack includes Python async with Playwright, Redis/Kafka/SQS, containerized workers, and cloud-native observability. Regards, Soas

@miscman

With my 13+ years of hands-on experience in full-stack development and specialization in API Development and Automation, I can confidently say I am an ideal candidate for your large-scale transaction system project. Over the course of my career, I have tackled complex challenges similar to yours, including the design and implementation of distributed automation architectures and orchestration of thousands of concurrent workflows. Moreover, I have a solid understanding of asynchronous processing, queues/workers (e.g., SQS, Kafka, Redis), and state management at scale - all crucial elements for your project. Adding further value to my candidacy is my familiarity with browser automation frameworks like Playwright and Puppeteer. Having worked on projects involving trading systems, I appreciate the meticulousness needed while working with simulated buying. Additionally, my skills aren't limited to ensuring that systems run smoothly: I have considerable expertise in debugging and problem-solving under real-world constraints to guarantee no interruption in service. Lastly, my proficiency in Python (async), as well as Go and Node.js (to a lesser extent), aligns perfectly with your requirements. Thank you.

@sasaprogramer21

You’re essentially building a controlled high scale behavior simulation platform, not simple automation. The hard parts will be orchestration at scale, state consistency across thousands of concurrent actors, and keeping flows realistic while maintaining reliability and observability. I’ve worked on high concurrency backend systems where we had to coordinate large volumes of parallel workflows with strong control over retries, partial success handling, and state recovery. Most failures at this scale come from weak queue design, poor session lifecycle management, and missing observability, so I design those first. How I would approach this Distributed worker architecture using Python async or Go depending on latency and throughput needs. Queue driven execution with Redis or Kafka to coordinate actors and maintain state transitions safely. Full observability stack with structured logs, metrics, and failure tracing so large runs stay debuggable. I am comfortable with Playwright based automation, large scale async processing, and building systems where reliability matters more than raw speed. Preferred stack Python async plus Redis or Kafka plus Playwright plus container based deployment. Availability Can start immediately and commit long term for the initial three to six month window. Best Alex

@ShekharTyagi345

Hi There, With 9 years of experience, I am the best fit for this project, given my background in building high-scale automation and simulation systems. How I will be completing this project: - Designing and implementing distributed automation / simulation architectures - Orchestrating thousands of concurrent workflows - Implementing observability and managing session state What tech stack I will be following: - Strong hands-on experience with Python (async) and Go - Experience with browser automation frameworks like Playwright - Solid understanding of queues, state management, and async processing I have worked on similar solutions in the past and have the relevant skills to tackle the challenges presented in this project. I have experience in trading systems, marketplaces, and load testing platforms, making me well-equipped for this role. Looking forward to the opportunity to work on this exciting project with you. Best, Shekhar Tyagi

@arbu1499

With over five years of senior backend/systems engineering experience and specialized skills in API development, backend development, and automation, I am well equipped to take on the challenge of designing and building high-scale automation and simulation systems for your procurement workflows. My deep understanding of Python (async), Go, and Node.js - which are vital to manage transaction-heavy systems like yours - will enable me to design and implement distributed automation/simulation architectures effectively. Having worked on projects involving load testing and simulation platforms, I have extensive experience with queues/workers such as SQS, Kafka, and Redis. This expertise will be invaluable as I orchestrate thousands of concurrent browser or API-based workflows for your project. Additionally, I've got hands-on experience with popular browser automation frameworks like Playwright and Puppeteer that could be pivotal in my role with this project. Moreover, I bring a solid understanding of async processing, strong debugging skills under real-world constraints, familiarity with behavioral modeling/user generation that aligns perfectly with what you're looking for. My conviction is that application development is relatively straightforward but engineering true systems require the ability to think architecturally. Let me bring my clarity of vision, technical acumen, and unflagging dedication to making our collaboration an unparalleled success.