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I will do custom api development rest api integration webhooks openai claude backend
Sathvic Kollu
About this gig
Need an API built or connected? I do custom API development and API integration, from one endpoint to a full REST API backend.
WHAT I BUILD
1. REST API and GraphQL development from scratch, clean and documented
2. Third party API integration with any service you already use
3. OpenAI and Claude API integration to add AI features to your app
4. Payment gateway, CRM, WhatsApp and shipping API connections
5. Webhooks that fire reliably, with retries when the other side is down
6. Authentication, API keys, rate limiting, JSON and error handling
7. Fixing an existing API that keeps breaking or timing out
8. Upgrading an old API without breaking what already uses it
BUILT PROPERLY
Every endpoint gets real error handling, not just a 200 and hope. Correct status codes, validation on every input, retries on failure, a Postman collection to test with, and Swagger docs your next developer can actually read.
Node.js, Express, NestJS, Python, FastAPI, Django, PHP, Laravel. Postgres, MySQL, MongoDB, Supabase, Firebase. Deployed to your server, AWS, or wherever you run things.
Message me with what you are connecting and what it needs to do. I will tell you honestly how long it takes.
Get to know Sathvic Kollu
Sathvic Kollu
AI agents Chatbot n8n automation REST APIs Full Stack Web and Mobile development
- FromIndia
- Member sinceMay 2021
- Avg. response time1 hour
- Last delivery3 days
Languages
Telugu, English, Hindi, Spanish, French, German, Italian, Arabic, Chinese, Urdu, Norwegian, Portuguese, Dutch, Greek, Czech, Indonesian, Japanese
I build AI agents, automations, and the systems they run on.
Most of my work starts one of two ways. Someone is doing by hand what a machine should do, or a developer left mid-project and it needs finishing.
What I build: AI agents and n8n workflow automation, REST APIs and integrations, full stack web apps with an admin panel, and mobile apps.
Node.js, Python, React, Laravel and Flutter, with OpenAI, Claude, or an open model on your own server.
You get the source code, on your own hosting, documented. Nothing is locked to me.
Message me your process and I will tell you what it takes.
My Portfolio
Other Software Development Services I Offer
FAQ
Which package should I choose?
Basic suits one small job, like connecting a form to a CRM. Most buyers need Standard: 8 endpoints with database and authentication. Premium is a full backend. Not sure? Message me what you are building and I will tell you which one fits.
What counts as one endpoint?
One endpoint is one action: create user, get orders, update a product. A contact form is usually 1. Basic create-read-update-delete for one thing is 4. Tell me what you need and I will count them for you before you order anything.
Do I get the source code?
Yes, in every package including Basic. You own it completely. I also hand over a Postman collection so you or your next developer can test every endpoint without needing me.
Can you fix or work with my existing API?
Yes, a lot of my work is exactly that. Send me the repository or the API docs and I will tell you honestly whether it is faster to fix or rebuild. I will not claim a rewrite is needed when it is not.
What do you need from me to get started?
What the API should do in plain words, access to any service it must connect to, and your hosting or database details if I am deploying. Send any documentation for the other side. I list everything the moment you order.
Which languages and frameworks do you work in?
Node.js with Express or NestJS, Python with FastAPI or Django, PHP with Laravel. Databases: Postgres, MySQL, MongoDB, Supabase, Firebase. If you already have a stack I match it rather than making you switch.
Will you deploy it or just send the code?
Either. Code only, or deployed to your own server, AWS, DigitalOcean or wherever you run things. Deployment is included at no extra cost, just tell me before we start so I can plan for it.
. What happens if it breaks after delivery?
If it does not work as described I fix it, and that does not count as a revision. Third party APIs also change over time, so I offer 30 days of support as an extra if you want me to keep it running.
