Custom software development company for startups and small businesses
Build your own slice of the future
Deepsel is a senior engineering team that designs, builds, launches and supports web, mobile and SaaS products. Our work runs in production for startups, small businesses and government organizations, from marketplaces and consumer apps to internal tools and SaaS platforms.
- 8+ years building software across industries
- 100+ products delivered and approved
- 20+ clients, from startup to government organizations
- 80% of clients come back with the next project
- 2 weeks from first call to a team at work
Our clients
Public and private organizations across the United States and Europe, from startups to government agencies.
Software development services
Eight things we do well, for a founder with a product to build, a team that needs more engineers, or a business whose old system has to be replaced.
AI and automation
Assistants, agents and workflow automation connected to your data and tools, tested against real cases before they go live.
Custom software development
We design and build the systems a company runs on: internal tools, customer portals, back-office automation and the integrations between them.
Web application development
Browser-based products that load quickly and work for every user, from an internal dashboard to a marketplace that takes bookings and payments.
Mobile app development
iOS and Android apps, native or cross-platform, from the first screen through store submission and the updates after it.
SaaS product development
Multi-tenant products with accounts, billing, roles and usage limits designed in from the start, so the platform holds as customers arrive.
Learn more →MVP development
A first version scoped to what wins early customers, built in short increments and in front of real users within weeks.
Learn more →Legacy modernization
Rebuilding systems that still run the business, in stages and without taking them offline. The Swiss federal login was rebuilt this way.
Learn more →Fractional CTO
Technical leadership for founders without a CTO: architecture, roadmap and hiring decisions, with a team to carry them out.
Learn more →Problems we solve for our clients
Most projects start with one of these. Here is what we do about each.
Slow release schedule
Two-week increments, each ending in a working version you can open. Progress is visible and dates hold.
The team is missing a skill
Senior engineers who join your repository and your standups within two weeks, for as long as the push lasts.
The last developer left and the code is a mystery
A codebase audit, documentation and a staged takeover, then fixes shipped in priority order.
The old system cannot be touched
Modernization in stages behind the running system, tested at each step, with a way back if anything breaks.
The product grew faster than the infrastructure
Cloud architecture, monitoring and load testing sized for the traffic you have and the traffic you expect.
Nobody can estimate the work
A discovery phase that ends in a written scope, architecture and timeline before any build begins.
Why clients choose us
Senior engineers from start to finish
The people on the discovery call are the people who write the code. Nothing is sold by one team and built by another.
Built for production, not for the demo
Every release is tested, monitored and documented before it reaches users. That holds for a first MVP and for a federal login system alike.
Your code, in your accounts
Repositories, cloud accounts and documentation belong to you from the first day. Leaving is a decision, not a migration project.
Small on purpose
A compact senior team and a short client list, so every project gets the founder's attention and nothing waits in a queue.
From the first call to a product in production
Five steps, each with something in writing at the end of it.
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Discovery call
Thirty minutes on what you are building, who it is for and what already exists. We say what we think, including when the right answer is a smaller build.
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Scope and estimate
We map users, workflows, integrations and risks, then put the scope, architecture, timeline and estimate in writing. It is yours to keep, whoever builds it.
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Design
Screens and data model drawn together, so what you approve is what gets built.
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Build and test
Two-week increments, each ending in a version you can click through. Automated tests, code review and load checks before launch.
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Launch and support
A staged rollout with a rollback plan, documentation and a handover session. Then we maintain the product, or hand it to your team.
The right team for the work
Three ways to work with us, depending on whether you need a product built, a roadmap carried, or a gap filled.
Project team
A full team for a defined product: scope, design, build and launch under one plan.
Best for: A new product, or a rebuild with a clear goal.
Discuss your projectDedicated team
Engineers, a lead and QA working your roadmap month after month, resized as priorities change.
Best for: A product that keeps evolving after launch.
Discuss your projectTeam extension
One or more senior engineers inside your existing team, your tools and your standups.
Best for: A skill gap or a deadline.
Discuss your projectReal projects we've shipped
From the Swiss federal login system to consumer apps, marketplaces and company websites: designed, built and run in production by this team.
Clubloungery
Booking.com for nightclubs. Guests pick a lounge directly on the floorplan and reserve in a few clicks; club owners draw their own bookable areas.
FitFoodies
An app to find healthy food around you: fitness-friendly dishes from nearby restaurants on a live map, filtered by dietary tags and nutrition values.
eIAM
The central login of the Swiss federal administration. We replaced the entire front end while the system stayed live, without touching the backend.
Result: Zero downtime during switchover
Experience across industries
From consumer apps to federal government, we have shipped software for teams in very different fields.
Marketplaces and hospitality
A booking marketplace where guests reserve a lounge on the club floorplan and owners draw their own bookable areas.
Health and wellness apps
A consumer app that finds healthy dishes nearby on a live map, filtered by diet and nutrition.
Government and public sector
The central login of the Swiss federal administration, rebuilt to the federal design system and accessibility standard.
Financial advisory
A mortgage and insurance advisory site with an integrated calculator that is ready the moment it is clicked.
Healthcare practices
A psychotherapy practice site built around one action: booking an appointment.
Professional services
An IT consultancy site with a three-dimensional logo rendered live in the browser.
Developer tools
Our own AI coding assistant, one of the first to understand a whole codebase on disk.
Technologies we work with
We pick the stack for the product and for the team that will maintain it after us.
React
Next.js
Vue
TypeScript
Astro
Tailwind CSS
Node.js
Python
FastAPI
Django
PostgreSQL
MongoDB
Redis
Docker
Kubernetes
AWS
Google Cloud
Flutter
Swift
Kotlin Frequently asked questions
What does Deepsel do?
We design, build, launch and support software for startups and small businesses: web and mobile apps, SaaS products, internal tools, AI automation and the modernization of systems that already exist. One team covers the whole path, from the first call to running the product in production.
Which industries do you have experience in?
Government, marketplaces and hospitality, consumer health, financial advisory, healthcare practices, professional services and developer tools. Most entries in the industries section above link to the project behind them.
How does a project start?
With a 30-minute call. We ask what you are building, who it is for and what exists today, and we tell you what we would do. If it makes sense to continue, a short discovery phase produces a written scope, architecture, timeline and estimate.
How long does it take to build a web or mobile app?
A first version usually takes weeks rather than months, because we scope it to what early customers need and build in two-week increments. A larger platform or a modernization takes longer, and the timeline is written down before the build starts.
How much does custom software development cost?
It depends on the scope, the integrations and the compliance the product carries. After discovery you receive a written estimate against a written scope; the ranges and the method are in our custom software development cost guide. We also say so when an existing tool would do the job and custom development is not worth it.
Can you take over or modernize a system that already exists?
Yes. We audit the codebase, document what we find and plan the work in stages, so the current system keeps running while it is replaced piece by piece. This is how the Swiss federal login was rebuilt.
Where is the team based, and how do we communicate?
Deepsel Inc. is a Delaware company. The engineering team works from Hanoi, Vietnam, with a daily overlap on US business hours. Calls, demos and documents are in English.
Who owns the code and the accounts?
You do. Work happens in your repositories and your cloud accounts from the first day, and the documentation is delivered with the product.
Do you provide support after launch?
Yes. We monitor, patch and extend the products we build for as long as you want us to, or we hand them over to your team with documentation and a walkthrough.