Expert Software & AI Development
We build custom software, mobile applications, and AI-powered systems for businesses that need thoughtful execution and real technical expertise.
Our Clients

























Who We Are
SQUAREONE is a software development company based in Seoul, Korea, with more than 15 years of experience building custom software, web applications, and mobile apps.
We bring deep domain expertise across AI, finance, crypto, gaming, ecommerce, sports, and other fast-moving sectors.
Our Team
We are a 40-person team partnering with startups, scaling companies, and enterprise organizations around the world to build scalable digital systems used by millions of people.
Combining strong engineering with real industry understanding, we deliver practical software solutions to complex business challenges.
What Sets Us Apart
Practical AI
We focus on AI that solves real business problems. That means building tools and systems that fit real workflows, support real teams, and create value beyond the prototype stage.
Tailored Solutions
Every business has different goals, systems, and constraints. We build software around what each client actually needs, not around one-size-fits-all templates.
Strong Execution
Good ideas only matter if they are delivered well. We put equal emphasis on planning, engineering quality, usability, and long-term maintainability.
Industry Understanding
We bring real domain knowledge across AI, finance, crypto, gaming, ecommerce, sports, and other fast-moving sectors. That helps us make better decisions and build solutions grounded in how each business actually works.
Built to Grow
Whether we are building for web, mobile, AI, or emerging technologies, we focus on creating products that are scalable, reliable, and ready to evolve over time.
Long-Term Partnership
We aim to be more than a delivery partner. We take ownership, communicate clearly, and build with the care needed to support lasting products and long-term relationships.
AI Systems for Automation and Growth
We design and deploy production-grade AI solutions for startups and enterprises.
What we are good at:
- LLM-powered applications
- AI copilots & assistants
- Recommendation engines
- Workflow automation
- AI agents
- Document processing
- Predictive analytics
- Fraud detection
- Customer insights

TESTIMONIAL
Client Feedback & Reviews
5.00
It was a complex project. Even though it was hard to understand the codebase at the beginning, the partner quickly analyzed it and helped set clear priorities, so we were able to keep things on track without delays. What stood out most was that when issues came up, they didn’t just give a quick fix. They explained multiple options and the reasoning behind each one. Communication was clear, and they regularly shared detailed progress updates, which made collaboration very smooth. If I had to point out one downside, it would be that when the schedule was tight, they sometimes aimed for a bit more perfection than necessary. However, the upside was that the final quality was excellent. Overall, they were responsible, highly professional, and I’d definitely want to work with them again on the next project.
This was a tough project without any reference point, and the timeline was extremely tight. They approached it like it was their own project—put real effort into planning, and constantly looked for the best possible solution. They also found a lot of information and details that I couldn’t have discovered on my own, which played a big role in making the project successful. The three scheduled meetings each week were always well-prepared and productive, and I’d especially like to recognize how much support and effort the team put in. This project succeeded because of them. The development team also had strong technical skills, so even with how challenging this was, they handled it very well. I’m confident that anyone who works with them will want to work with them again. I would recommend them without hesitation, and honestly, I want to do every future project with them. They’re truly one of the best professionals I’ve worked with.
We started the project with a lot of uncertainty because the requirements were still changing and not fully organized, so I was honestly quite concerned at first. But as the work progressed, that concern gradually disappeared. What I appreciated most was that they did not just build what we asked for mechanically. They thought carefully about what would make the most sense from an actual service and operations perspective, and they proactively suggested better directions. Speed mattered, of course, but what impressed me even more was their communication style. They consistently shared progress in a transparent way, and whenever an issue came up, they did not try to gloss over it. Instead, they clearly explained the available options and the expected impact of each one, which made it much easier for us to make decisions with confidence. Even during the most time-sensitive parts of the schedule, they never seemed willing to compromise on quality, and the final result reflected that. It felt less like working with an outsourced development company and more like working with a true project partner. If we do a similar project again, they will be the first team I reach out to.
They were the true professionals. They pointed out details I hadn't considered, from a developer’s perspective, and they were incredibly thorough. During the project, for items that absolutely needed to be discussed, they pushed for proper alignment even if it meant spending more time rather than letting things slide. We didn’t have a formal “mid-project report” process, but in reality they were updating us almost every day, organizing what was needed and explaining it clearly. When necessary, they even presented directly. From the client side, this approach felt much safer and I was extremely satisfied. Thank you to the project manager, developers, and designers who worked on our project.
This project involved building a React-based WYSIWYG editor, and then developing a customer-facing web application that collects responses through forms created with that editor. After we shared the requirements, they delivered the planning documents in a clean and structured way, and they reflected feedback well. We requested that the design deliverables be provided in Figma, and they were very accommodating. The design output was also neat and exactly what we wanted. They clearly have strong front-end capabilities, and both speed and quality were solid.
This was our first time running a project like this, and because the partner had prior experience, you could really feel their professionalism. They completed the work within the timeline we wanted, and communication across teams was smooth. The strong points were the satisfying end result and fast feedback. Most of all, I really appreciated how much effort they put in to meet the agreed schedule.
Tech Stack
AI / Machine Learning
- PyTorch
- TensorFlow
- scikit-learn
- Hugging Face
- OpenAI API
- LangChain
- LlamaIndex
- vLLM
- Ollama
- DSPy
- Qdrant
- Pinecone
- RAG
- MLflow
- W&B
- FastAPI
- BentoML
- Docker
- Kubernetes
- Amazon SageMaker
Web and Mobile
- React Native
- SwiftUI
- Flutter
- Java
- Kotlin
Data and Infrastructure
- PostgreSQL
- MySQL
- MongoDB
- Clickhouse
- Redis
- Elasticsearch
- RabbitMQ
- Kafka
Cloud and DevOps
- Amazon Web Services
- Docker
- Kubernetes
- Terraform
- GitHub Actions
Blockchain / Web3
- Solidity
- Rust
- Anchor
- Hardhat
- Foundry
- Ethers.js
- Viem
- Solana Web3.js
- SPL Token
- Metaplex
- OpenZeppelin
- ERC-20
- ERC-721
- ERC-1155
- ERC-165
- ERC-173
- ERC-2981
- ERC-4337
Gaming / Real-Time Systems
- Unity
- Unreal Engine
- PixiJS
- Three.js
- WebSockets
- cocos2d-x
Front-End
- React
- Next.js
- TypeScript
- Tailwind CSS
Back-End
- Python
- Node.js
- Go
- Java
- C#
- Rust
Design
- Figma
- Photoshop
- Illustrator
- After Effects
- Premiere Pro