I will fix your backend bug or API issue

A
agustin_devel
A
agustin_devel
Agustin O.

About this gig

Your API is broken and you don't have time to dig through it yourself. 

I do.


I'm a backend developer with 5+ years of experience working with 

Node.js, Python, Go, Java, and C#. I fix bugs fast, explain what 

caused them, and make sure they don't come back.


WHAT I FIX:

API endpoints returning wrong data or crashing

Authentication/authorization issues (JWT, OAuth, sessions)

Database query bugs (Postgres, MySQL, MongoDB)

Integration failures (third-party APIs, webhooks, payment gateways)

Performance issues (slow endpoints, N+1 queries)

Deployment/environment bugs


HOW IT WORKS:

1. Send me your repo (GitHub/GitLab) or relevant code + error logs

2. I diagnose the issue and give you a quick estimate of time needed

3. I fix it, test it, and explain what went wrong

4. You review and confirm


WHY WORK WITH ME:

I don't just patch the symptom I find the actual root cause so 

the bug doesn't come back in a different form next week. You'll 

get a short explanation of what broke and why, in plain language.


Send me a message with details before ordering if your case is 

unusual or the bug is hard to describe happy to take a quick 

look for free to confirm I can help.

Respect third-party rights

Please be aware that it is against Fiverr's policies for sellers to include themes, templates, or any other elements that infringe third-party rights or applicable laws in the delivered work. Read more about in our Guide to Responsible Digital Creation.

Get to know Agustin O.

Agustin O.

High Performance Web and Desktop Software Engineer

  • FromArgentina
  • Member sinceAug 2026
  • Languages

    Spanish, English
I am a Software Engineer with experience building offline-first ERP systems and interactive AI-powered platforms. I specialize in full-stack development using TypeScript, Python, and Go, with a focus on optimizing database performance and implementing scalable architectures like Microservices and DDD.

My Portfolio