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Fiverr Pro
English
$
USD
I will integrate rest API, fix node js backend bugs stripe webhooks graphql openai API
Esther B
About this gig
Need a reliable backend developer to integrate APIs or fix frustrating backend issues? You've come to the right place.
I specialize in API integration, backend bug fixing, authentication, payment gateways, webhooks, databases, and server-side development using Node.js, Express.js, JavaScript, REST APIs, PostgreSQL, MongoDB, Firebase, Supabase, and AWS. Whether you're building a SaaS platform, AI application, eCommerce store, mobile app, or custom web application, I'll deliver clean, secure, and scalable backend solutions.
My services include:
- REST API Integration
- Third-Party API Integration
- OpenAI API Integration
- Stripe & PayPal Integration
- Webhook Development & Fixes
- Backend Bug Fixing
- Node.js & Express.js Development
- JWT & OAuth Authentication
- Firebase & Supabase Integration
- PostgreSQL & MongoDB Support
- Database Optimization
- API Error Debugging
- Performance Optimization
- Deployment & Server Configuration
- Backend Security Improvements
Please contact me before placing an order so I can review your requirements and recommend the best package. I look forward to helping you build, integrate, or fix your backend quickly and professionally.
Get to know Esther B
Esther B
Backend Developer, API Integration, Node js, Supabase, Firebase, AWS, PostgreSQL
- FromGermany
- Member sinceJul 2026
- Avg. response time8 hours
Languages
German, English, Spanish, French, Italian
Backend developer specializing in scalable APIs, database architecture, and secure web applications. I build REST APIs, backend systems, authentication, payment gateways, AI integrations, and automation workflows using Node.js, Express.js, Supabase, Firebase, PostgreSQL, MongoDB, AWS, and SQL. I integrate Stripe, webhooks, third-party APIs, CRMs, and cloud services while optimizing performance, security, and scalability for SaaS, AI, eCommerce, and custom web applications. I also develop serverless functions, API debugging, cloud deployment, database optimization, and custom backend solutions.
Other Software Development Services I Offer
FAQ
Can you integrate any REST API into my application?
Yes. I integrate REST APIs, third-party services, payment gateways, AI APIs, CRMs, and custom APIs into web and mobile applications. I ensure secure authentication, proper error handling, complete testing, and reliable data flow between your systems.
Can you fix my existing backend without rebuilding everything?
Absolutely. I first identify the root cause, then fix only the affected components while preserving your existing architecture whenever possible. This minimizes downtime, reduces costs, and keeps your application running smoothly.
Do you work with Stripe, PayPal and payment gateways?
Yes. I integrate and troubleshoot Stripe, PayPal, subscriptions, one-time payments, webhooks, checkout flows, and payment verification. I ensure transactions are secure, reliable, and work correctly from start to finish.
Can you fix API errors and webhook failures?
Yes. I resolve API connection issues, authentication errors, webhook failures, invalid responses, timeout problems, and data synchronization issues. I thoroughly test every integration to ensure dependable communication between all connected services.
Which backend technologies do you support?
I work with Node.js, Express.js, JavaScript, PostgreSQL, MongoDB, Firebase, Supabase, REST APIs, JWT, OAuth, Stripe, PayPal, AWS, webhooks, and many third-party APIs. Feel free to contact me if your stack isn't listed.
Can you solve authentication and login problems?
Yes. I fix JWT authentication, OAuth, Firebase Auth, Supabase Auth, session management, token refresh, role-based permissions, and authorization issues while following modern backend security best practices.
Do you optimize backend performance?
Yes. I improve API response times, optimize database queries, eliminate bottlenecks, reduce server load, and enhance scalability. My goal is to make your backend faster, more stable, and capable of handling higher traffic efficiently.
Can you fix database issues and connection errors?
Absolutely. I troubleshoot PostgreSQL, MongoDB, Firebase, and Supabase issues including failed connections, slow queries, schema problems, migrations, indexing, and data consistency to improve performance and reliability.
What do you need before starting my project?
Please provide your project requirements, source code or repository access, API documentation, error messages, screenshots, hosting details, and any relevant credentials. Complete information allows me to start quickly and deliver accurate results.
Why should I contact you before placing an order?
Every backend project is different. Contacting me first allows me to evaluate your requirements, recommend the right package, estimate delivery accurately, and ensure the solution matches your goals without unexpected costs or delays.
