I will fix bugs and issues in web and mobile applications

C
callidusdev
C
callidusdev
Nevfel Gul
fix bugs and issues in web and mobile applications
Full Screen
fix bugs and issues in web and mobile applications

About this gig

I will investigate and fix bugs in your web or mobile application.

I can help with issues related to:

React and React Native

JavaScript and TypeScript

Firebase and Firestore

Authentication and login issues

API integration errors

UI and responsive layout problems

Broken features and unexpected behavior

Expo and mobile app issues

Database and data fetching problems

Before placing an order, please contact me and briefly explain the issue. If possible, include screenshots, error messages, or steps to reproduce the bug.

The listed package covers one bug or issue. For complex problems or multiple bugs, I can provide a custom offer after reviewing the project.

My goal is to identify the cause of the problem, fix it cleanly, and keep the existing structure of your project intact.

  • Programming language

    • JavaScript

  • Expertise

    • Algorithms & Data structures
    • Debugging
    • Performance
    • Security
    • Design

  • Frontend framework

    • Flutter
    • Next.js
    • React.js
    • Three.js
    • Htmx

  • Backend framework

    • FastAPI
    • Next.js
    • Node.js
    • Firebase
    • Spring Boot

Get to know Nevfel Gul

Nevfel Gul

Founder and Technical Lead

  • FromTurkey
  • Member sinceSep 2026

  • Languages

    Turkish, English
I am a Computer Engineer and founder of Callidus, a digital studio specializing in full-stack web and mobile development, UI/UX, and automation. We bridge scalable technical architecture (React, React Native, TypeScript, Firebase) with modern design (Figma). Whether you need a cross-platform mobile app or a robust web platform, my team delivers complete solutions. We handle everything from initial prototyping and database structuring to final deployment and app store publishing. Let’s build highly optimized, ready-to-scale digital products.

My Portfolio

Other Software Development Services I Offer

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