I will build backend apis, saas auth, stripe payments and ai integrations


About this gig
Need your product's backend to work reliably across accounts, data and external services?
I build Python/FastAPI and TypeScript/Node.js APIs with PostgreSQL/Supabase. My paid work includes SaaS authentication, Stripe payments, usage credits and AI integrations.
I can help with:
- API endpoints, webhooks and database-backed workflows
- Authentication, roles and access controls
- Stripe payments and a clearly defined credits model
- AI API integrations and connections to external services
- Workflow tests, setup documentation and source-code handoff
Basic covers one defined API workflow OR one provider integration. Standard connects up to three API workflows, one integration and a PostgreSQL data flow. Premium covers one auth provider, one payment provider and a simple agreed credits model.
Message me before ordering so we can agree on inputs, outputs, acceptance criteria and existing-code access. Complex billing, migrations, major frontend work and ongoing maintenance require separate scope. Hosting and provider fees are paid by you. Revisions refine the agreed functionality.
Get to know Clayton George
Full Stack, Backend and Data Engineer
- FromUnited States
- Member sinceAug 2018
Languages
English, German
My Portfolio
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FAQ
What should we agree on before I order?
We will define the workflow, required providers, data model, inputs and outputs, acceptance criteria and existing code. Send a brief and any relevant API documentation first so I can confirm the right scope and package.
Does every package include authentication and payments?
No. Basic covers one API workflow OR one provider integration. Standard connects up to three API workflows and one integration. Premium includes one auth provider, one payment provider and a simple agreed credits model. We define all details before ordering.
Can you work with my existing application?
Yes, subject to a review of the stack and the agreed integration points. I work with Python/FastAPI, TypeScript/Node.js and PostgreSQL/Supabase. Large refactors, migrations or unrelated features need separate scope.
What does an AI integration include?
A defined application workflow using an agreed AI provider or external service, with clear inputs and outputs. Model training, broad autonomous-agent systems, evaluation datasets and ongoing provider usage are not automatically included.
What will I receive?
The agreed backend functionality, source code, relevant workflow tests and setup/handoff notes. Deployment assistance can be included when agreed in scope. You supply the hosting and provider accounts and pay their usage fees.
How do revisions and support work?
Revisions refine functionality already agreed for the order. New features, changed requirements, complex billing and ongoing maintenance require a separate scope. I share written progress and document the handoff.
Can you also build the frontend?
Yes. I also build React and Next.js web applications, SaaS MVPs and dashboards. This Gig focuses on backend systems and integrations; major frontend work is scoped separately. Tell me which part of your application needs to be delivered.

