Back-end. Python, fast API, postgres, aws, cognito, celery, play market payment.
267 USD Client's review of cooperation with Oleksandr Z.
Back-end. Python, fast API, postgres, aws, cognito, celery, play market payment.Completes on time and in full.
Freelancer's review of cooperation with Julia Khimiy
Back-end. Python, fast API, postgres, aws, cognito, celery, play market payment.Everything is great, the collaboration is very easy, I received some useful advice from the client. Everything is 10/10, we continue the collaboration.
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30 days445 USD
30 days445 USD
I will eliminate user loss at the registration stage by reconfiguring Celery queues for guaranteed delivery of AWS Cognito codes, and I will fix the validation logic for Play Market Billing checks on the backend.
What specific technical method are you currently using to process transactions: do you have Google Cloud Pub/Sub and Real-time Developer Notifications (RTDN) for Play Market connected so that your FastAPI reliably receives payment statuses (refunds, cancellations, success) directly from Google servers, avoiding desynchronization of the Postgres database with the actual state of purchases?
The audit plan for asynchronous tasks and the exact budget for fixing these critical bugs is ready to be discussed in personal correspondence. 🤝
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1 day67 USD
1 day67 USD
Good day. I am a Middle Python Developer with over 3 years of commercial experience. To accurately assess the timelines and costs, it is necessary to review the code, as the errors can vary greatly in complexity and time to fix.
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3 days67 USD
162 3 days67 USD
Good day.
I am familiar with the stack and have extensive experience with FastAPI and databases. I have fixed similar bugs with Google Play payments.
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3 days67 USD
261 3 days67 USD
Hello!
I am interested in your project. I have experience working with Python backend and setting up the logic of mobile services. I have a good understanding of client-server interaction architecture, which is critical for both of your tasks.
How I plan to solve your tasks:
Play Market Payments: I will analyze the logic of processing Webhooks from Google Play. Often the problem lies in the validation of the purchase token on the server side or in delays in updating the status in the database. I will check the logs, fix payment processing errors, and ensure the correct accrual of in-game services.
Resend confirmation code: I will optimize the resend mechanism (Rate Limiting). I will set up correct timers (for example, 60 seconds before a resend request) and check the integration with your SMS gateway or Email service to ensure codes are sent reliably and without duplication.
…
Why you should choose me:
Linux/Python stack: I work in a Linux environment, which allows for quick deployment and testing of backend solutions.
Security: As a cybersecurity specialist, I pay special attention to protecting transactions and preventing the interception of confirmation codes.
Clean code: I write structured code that is easy to maintain in the future.
I am ready to conduct an audit of the current implementation and start making corrections today. Please message me privately to discuss access to the code and details of the technical specifications.
Best regards!
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1 day67 USD
656 9 0 1 day67 USD
Good day, Julia!
In general, the task is clear, but for an accurate response regarding deadlines and price, I would like to clarify some questions that arose after analyzing your task.
Please write in private messages – we will discuss the details and your wishes.
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3 days89 USD
3355 11 0 3 days89 USD
Hello, Yulia! I am Nina, the manager of engineer-architect Valentin.
We are ready to promptly conduct an audit of your backend and fix errors in the financial logic and registration system. Valentin specializes in Python/FastAPI and has experience with AWS infrastructure.
Our action plan:
Play Market Billing: We will set up reliable server-side receipt verification and status synchronization through Google RTDN. This will eliminate situations where the payment has gone through, but access in the game has not appeared.
AWS Cognito & OTP: We will refine the logic of resend_confirmation_code. We will implement a Rate Limiting mechanism (via Redis or Postgres) to avoid spam blocks from AWS and ensure correct timers for users.
…
Celery/AWS Infra: We will check the task queues that process payments to eliminate possible transaction "hangs."
Valentin works on the principle of "first clean architecture, then code," so the fixes will not break adjacent modules.
Budget: 3000–5000 UAH (depending on the state of the current code).
Deadline: 2–3 days.
Yulia, do you have Real-time Developer Notifications (RTDN) from Google enabled, or are we currently relying only on requests from the application?
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3 days67 USD
285 2 0 3 days67 USD
Hello! I have experience working with PostgreSQL and integrating payment systems. The task of fixing payment errors in the Play Market and setting up Resend is clear to me. Although the main project stack is Python/FastAPI, I confidently work with similar architectures and API integrations.
What I offer:
Play Market: I will analyze the transaction processing logic and fix errors in the backend.
Resend: I will set up stable sending of confirmation codes during registration.
Databases: I will optimize queries to Postgres if necessary for stable operation.
I am ready to start the code audit immediately after gaining access. Estimated completion time: 2–4 days.
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3 days67 USD
981 6 3 3 days67 USD
Good day, madam!
I am ready to complete your task!
Write in private messages, we will discuss your project and agree on the price.
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Winning proposal8 days267 USD
1495 13 0 Winning proposal8 days267 USD
Hello! I can implement it. Write to me privately to discuss all the details. I will be glad to cooperate!
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1 day67 USD
11596 44 0 1 day67 USD
Hello, I will make the changes, I have the relevant experience.
Write to me privately.
I will be happy to help you!
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2 days67 USD
284 2 days67 USD
Python, FastAPI, PostgreSQL, AWS, Cognito, Celery — the stack fully matches my experience. I have worked with Google Play Billing API (server-side purchase verification, processing webhooks from Google), integrating AWS Cognito (including custom registration flows, resend verification code). I understand the specifics of asynchronous processing through Celery. To provide a more accurate estimate — I need to look at the error logs and the current implementation of the payment flow. I am ready to connect and quickly figure it out.
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1 day67 USD
96304 1273 1 10 1 day67 USD
Hello. I have extensive experience with FastAPI. Can I review the project and the edits?
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3 days67 USD
4975 41 4 1 3 days67 USD
Good day!
As a Back-end developer in Python with experience in FastAPI, PostgreSQL, AWS, Cognito, and Celery, I am ready to effectively fix the payment errors in Play Market and refine the resend confirmation code feature for your game Lila.
Message me privately, and we will clarify the details.
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1 day67 USD
1 day67 USD
Hello!
We are dZENcode – a full-cycle digital solutions development company.
We take on projects from scratch and connect to the refinement of existing solutions.
We are ready to quickly connect and help with backend refinement.
1. What specific payment errors in the Play Market need to be fixed first?
2. What is currently happening with the resending of the confirmation code during registration?
… You can find detailed information about our services and projects in the profile:
Freelancehunt
Please take a look – after that we can discuss the details and agree on the next step.
⚠️ After clarifying all the details, we will determine the scope, the appropriate format of cooperation: by tasks, outsourcing, or outstaffing, and the final cost.
Why projects with us are guaranteed to reach release:
💎 10+ years providing IT services;
🔥 90+ in-house specialists;
🚀 250+ public reviews since 2015;
⚙️ We support the product under SLA after launch;
✅ We work under NDA and a contract with the company!
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7 days67 USD
7 days67 USD
Hello, I have been working on a mobile application for psychological coaching with integration of Google Play payments and a user verification system, which processes 500+ transactions daily.
I wonder if the payment errors are related to webhooks from Google Play or to the validation of receipts on the backend?
I suggest we get in touch, I will provide you with free technical consultation and we will create a development plan + I will tell you about my team!
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1 day67 USD
1738 9 0 1 day67 USD
Good day, I have experience working with Python as well as Telegram bots, I can complete everything quickly and efficiently, write to me and we will discuss the details.
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1 day67 USD
172 1 1 1 day67 USD
Good day. I am ready to complete this project as I have extensive experience in application development.
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2 days67 USD
162 2 days67 USD
Good day! I have worked with the same technology stack with financial companies. I propose to conduct an error analysis, and then we will create a correction plan and implement it!
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3 days67 USD
937 5 0 1 3 days67 USD
Hello! I am Volodymyr, the founder of the engineering agency Vaysed. The project of the transformational game "Lila" is a wonderful psychological tool, and to maintain high user trust, it requires absolutely flawless operation of the financial part and the authorization system. We specialize in the development and support of fault-tolerant IT systems, so we are ready to promptly address these technical debts at the highest engineering level.
Payment issues in the Google Play Market most often arise due to desynchronization between the client application, your server, and the Google Play Billing API. For strict transaction fixation, we will not only fix visual errors on the frontend but also set up reliable server-side validation of purchase tokens based on Node.js or Python. Using a state machine architecture will allow the backend to clearly distinguish payment statuses, ensuring that the user receives paid content only after actual confirmation from Google, and that money never "hangs" in the air.
Regarding the improvement of the OTP (One-Time Password) resending system during registration, we will implement this mechanism securely and reliably. Instead of simply adding a timer button, we will tie the logic to the Redis message broker. This will not only guarantee timely delivery of codes but also implement reliable protection against spam attacks (Rate Limit), limiting the number of code requests from a single device. This approach will protect your budget for mailings and ensure a smooth user experience.
You can evaluate our engineering approach and implemented cases on the agency's website: https://vaysed.me/. Message me privately so we can agree on the details and promptly start working on your project!
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2 days67 USD
512 2 days67 USD
Hello!
I will fix the payment errors in Google Play and complete the resending of the confirmation code.
Payments: I will check the correspondence of product IDs, statuses in the console, the test environment, and the integration of Google Play Billing in Unity.
Confirmation code: we will add ForceResendingToken + cooldown timer via Firebase Auth.
To get started, please provide access to Google Play Console, Firebase, and the game code. Ready.
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1 day67 USD
650 2 0 1 day67 USD
Good day, Julia!
I see the problem — bugs with payments on Play Market and resend of the confirmation code on FastAPI + Celery stack. I will figure it out in the first hour: I will connect to the repo, find the point of failure, and fix it. I am ready to start now.
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