I will fix rest API authentication, cors, webhook and integration issues


About this gig
Is your REST API connected but not working correctly?
Maybe you're getting authentication errors, your webhook isn't firing, CORS is blocking requests, or data isn't syncing between systems.
I help troubleshoot and fix broken REST API integrations.
I can fix:
- REST API errors (400, 401, 403, 404, 500)
- Authentication, API keys and token issues
- CORS and cross-origin problems
- Webhook failures and incorrect payloads
- JSON request/response and data mapping issues
- Data synchronization problems
- Third-party API connection errors
- Endpoint, parameter and header issues
- Backend API integration bugs
I don't just explain the error. I investigate the request, response, authentication and data flow to identify where the integration is breaking, apply the appropriate fix and test the result.
Whether you're connecting a website to a third-party service, sending data through webhooks, or connecting two systems through REST API, I'll help get the integration working correctly.
Please provide your API documentation, error details/logs, relevant code or setup and explain what happens now versus what you expect.
For complex projects involving multiple APIs or workflows, message me before ordering.
Get to know Blessing D
Nodejs, API and Automation Problem Solver
- FromNigeria
- Member sinceMar 2026
- Last delivery2 months
Languages
English, Spanish
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Other Software Development Services I Offer
FAQ
What REST API problems can you fix?
I can troubleshoot API errors, authentication, CORS, webhooks, JSON mapping, data sync, endpoints and third-party API integration issues.
Can you fix an API that was working before but stopped?
Yes. I can investigate the existing integration, identify what is causing the failure and apply the appropriate fix.
Can you fix webhook issues?
Yes. I can troubleshoot webhook triggers, endpoints, payloads, authentication and data delivery problems.
Can you fix 400, 401, 403, 404 or 500 errors?
Yes. I can investigate the request and response to identify the cause and implement a suitable fix.
Do you work with third-party APIs?
Yes. I can troubleshoot third-party API integrations when the required documentation and access are available.
What do you need before starting?
Please provide the API documentation, error details or logs, relevant code/setup, and explain what should happen versus what happens now.
Can you guarantee that my API will work?
Yes, I will troubleshoot and fix the issues within the accessible integration and test the solution. Third-party outages, restrictions, or undocumented changes may be outside my control.
2 reviews for this Gig
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Rating Breakdown
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- Quality of delivery
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K keithprecise

United States
Everything was done professionally and correct
2 days
Duration
Helpful?K keithprecise

United States
The project completed exactly how I want. Did everything on time and professional
3 days
Duration
B 
Seller's Response
Helpful?
2 reviews for this Gig
| (2) | ||
| (0) | ||
| (0) | ||
| (0) | ||
| (0) |
Rating Breakdown
- Seller communication level
- Quality of delivery
- Value of delivery
Sort By
K keithprecise

United States
Everything was done professionally and correct
2 days
Duration
Helpful?K keithprecise

United States
The project completed exactly how I want. Did everything on time and professional
3 days
Duration
B 
Seller's Response
Helpful?

