Browse categories
Explore
Fiverr Pro
English
$
USD
I will be your backend developer for nodejs, nestjs and rest apis
Kai k.
Level 1
5.0
5.0
About this gig
Senior Backend Developer | 9+ Years Experience | 125+ SaaS Projects | 100% Satisfaction | Certified Expert
Most products dont break at launch they break when users start showing up.
If the backend isn't designed for growth, everything slows down, fails, or needs a rewrite.
I build backend systems that stay stable, secure, and easy to extend even after months or years of real usage.
No rewrites. No data chaos. No scaling surprises.
I'm Kai, a backend developer with 9+ years of shipping real SaaS systems APIs, databases, authentication, and integrations used daily by real users.
Why this works
- Built for scale, not quick launches
- Clean backend architecture teams can grow on
- Secure auth & data handling from day one
- Databases structured for long-term growth
- Clear communication, zero guesswork
Tech I build with
- Node.js, Express, NestJS
- JavaScript & TypeScript
- PostgreSQL, MongoDB, MySQL
- Supabase, Firebase
- REST APIs, webhooks, Stripe & external APIs
Message me before ordering.
I'll tell you what to build, what to avoid, and how to keep your backend future-proof.
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 Kai k.
Kai k.
Senior Software Engineer
Level 1
- FromUnited Kingdom
- Member sinceSep 2025
- Avg. response time1 hour
- Last delivery1 month
Languages
English, German, French, Spanish, Arabic
Senior Full Stack Developer | React | Node.Js | Supabase | AI SAAS | AI agents | AI Chatbots
Hi! I’m a Sr. Full Stack Developer with 9+ years of experience delivering scalable, MVPs and enterprise-level web applications for clients globally.
What I Offer
✅ Custom Web Applications (React, Next.js, Node.js)
✅ Enterprise SaaS Development (multi-tenant, scalable systems)
✅ API Development & Integrations (REST, Webhooks, CRMs)
✅ Admin Dashboards & CMS Solutions
✅ Industry Solutions: Real Estate, Education, Retail & eCommerce, Logistics, Energy, Aviation, Healthcare
Let's Start - Order Now
My Portfolio
FAQ
Why should I message you before ordering?
Because a quick discussion upfront helps avoid bad architecture choices that cost time and money later.
What type of backend projects do you handle?
I work on production SaaS backends APIs, databases, authentication systems, and integrations for apps that need to scale. Not demos or throwaway setups.
Can you fix or improve an existing backend?
Yes. I often refactor, stabilize, and scale live systems without breaking what’s already in use.
Do you build backends from scratch?
Absolutely. I design clean backend architecture from day one, so growth doesn’t require rewrites later.
Which technologies do you use?
Node.js, Express, NestJS, JavaScript/TypeScript, PostgreSQL, MongoDB, MySQL, Supabase, Firebase, REST APIs, webhooks, and Stripe integrations.
Is security and scalability included?
Yes. Security, performance, and scalability are built in, not added later as fixes.
Will this work with my frontend or team?
Yes. I build clear APIs and documentation so frontend teams and other developers can work smoothly.
Do you communicate during the project?
Yes. You’ll always know what’s done, what’s next, and why no guesswork.
Reviews
4 reviews for this Gig
| (4) | ||
| (0) | ||
| (0) | ||
| (0) | ||
| (0) |
Rating Breakdown
- Seller communication level
- Quality of delivery
- Value of delivery
Sort By
Most relevant
B brown1865
United States
Good attention to detail. Identified the validation bug and fixed it properly instead of applying a quick patch. Reliable developer with solid backend knowledge.
Up to $50
Price
4 days
Duration
Helpful?L laura_evans25
United States
Very good Programmer, I will work with him in future.
$400-$600
Price
1 day
Duration
Helpful?S stevesmith23212
United States
Found the bug fast and fixed it properly. Smooth experience.
Up to $50
Price
2 days
Duration
Helpful?B bet231
United States
Knew exactly what to do and delivered without issues.
Up to $50
Price
1 day
Duration
Helpful?
Reviews
4 reviews for this Gig
| (4) | ||
| (0) | ||
| (0) | ||
| (0) | ||
| (0) |
Rating Breakdown
- Seller communication level
- Quality of delivery
- Value of delivery
Sort By
Most relevant
B brown1865
United States
Good attention to detail. Identified the validation bug and fixed it properly instead of applying a quick patch. Reliable developer with solid backend knowledge.
Up to $50
Price
4 days
Duration
Helpful?L laura_evans25
United States
Very good Programmer, I will work with him in future.
$400-$600
Price
1 day
Duration
Helpful?S stevesmith23212
United States
Found the bug fast and fixed it properly. Smooth experience.
Up to $50
Price
2 days
Duration
Helpful?B bet231
United States
Knew exactly what to do and delivered without issues.
Up to $50
Price
1 day
Duration
Helpful?
