We offer you access to top European tech talent
Circle Square Limited is a London headquartered software development company, offering the brightest Eastern European software development specialists to suit the needs of our clients. While our main team of developers is based in Ukraine, with the support of our UK team, we distinguish ourselves by adherence to Western standards in communication, quality and delivery. Among our clients we count both start ups and NASDAQ listed companies, but we are committed to meeting the expectations of our clients regardless of size and financial standing.
Our primary specialization is the following:
WEB DEVELOPMENT:
• websites and landing pages
• e-commerces and marketplaces
• SaaS applications
MOBILE DEVELOPMENT:
• native mobile development
• cross-platform development
DESIGN:
• web design
• mobile app design
Out main tech stack is:
• React, Redux, TypeScript, HTML, CSS
• NodeJS
• Swift, ObjectiveC, Java
• React Native, Xamarin
Recommended Providers
Focus
Portfolio
YOW, TraWell, On-Game

YOW
Discover
YOW is a mobile application that functions as a travel scratch map. In the beginning, your travel map is black, but whenever you visit a new country, city or street it unveils an area, which was black before and marks the place you have been to. The map is based on the API of Google Maps. You can build a list of favourite places and use navigation for finding new spots.
Share with friends
Your friend asks you for travel recommendations and you struggle for answers? Now you can let your friends know how many countries/cities/venues you have been to and offer recommendations. The app allows its users to share their exploration progress using social media (Facebook, Twitter, Google+...)
Our Features
Our technical team used a comprehensive set of tools and technologies during app development.
· Offline Working
YOW works offline, through GPS, so there is no need to constantly look for Wi-Fi.
· Storing Pictures
Every time you take your finest snapshots you can attach them to the locations where they were taken using the app.
· Smart Adviser
Whether you are visiting an old favourite location or on an exciting exploration trip, the app will give you suggestions of places to see nearby.

TraWell
TraWell is an online web service created on the instruction of an international travel company, which helps customers plan their journeys in advance. The service allows customers to pre-book and pay for flights, cruises, cars, vacation packages and entertainment events online and leave reviews about their experiences. The site integrates multiple global flight and hotel reservation platforms, such as Amadeus, Pegasus, Sabre and Worldspan, with a proprietary hotel reservation system for contracted, bulk-rate reservations.
· NLP entity linking
A natural language processing entity was linked to the search platform to enhance search performance.
· Invoicing system
An automated invoicing system, which creates invoices, sends payment reminders, keeps track of business expenses was integrated into the web service.
· Payment system
To accept online payments from customers worldwide, the web service relies on a link with a third party international payment platform.

On-Game
Unique Challenge
Improve desktop app performance two-fold and mobile app performance from 30 seconds to 10 seconds.
Challenge Accepted
The Circle Square tech team tracked and optimized the app’s performance as well as response time, monitored for multiple devices and compared different operating systems and networks for app functioning.
Performance Improvement
Desktop app performance was improved from 9 seconds to 5 seconds, mobile app performance was drastically improved from 30 seconds to 4 seconds.
Variety of sports
The application allows users to follow more than 10 different types of sports, including Football, Basketball, Baseball, Hockey, Tennis, and Golf.
Real-time updates
ON-GAME enables users to build a personalized feed and get the latest game updates. Users can customize it in order to get instant alerts for upcoming games. Live commentary is included to show minute-by-minute match highlights.
Statistics
The application offers access to detailed statistics, schedules, team standings, fixtures, pre-match lineups, close game situations.
Reviews
the project
MVP & CRM Dev for Health Tech Startup
"The team aimed to find solutions to our problem as quickly as possible."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
I am the Head of Product Design of a London-based health-tech start-up backed by global investors. We provide a leading platform addressing the social determinants of health. Our solution empowers health and social care professionals to connect people to a broad range of community activities and generates data to prove the health outcomes of these initiatives.
For what projects/services did your company hire Circle Square, and what were your goals?
We initially hired Circle Square to complete the development of an MVP for an activities marketplace. We then continued to work with them for almost two years, adding additional features to the MVP, developing a patient management application (CRM) and an insights dashboard, as well as integrating with various NHS APIs.
How did you select this vendor and what were the deciding factors?
We were introduced to Circle Square in November 2019. During a meeting at our London offices we explained our need to complete an MVP using Ruby on Rails to build on legacy code that we had inherited from previous developers. Circle Square clearly outlined the step by step process for completing the MVP and clarified the scope in order to provide a fixed price quote.
Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.
The objective of the initial phase of the project was to create an MVP for a local marketplace of community activities, which is used by councils and charities to link people to local initiatives. The project was then expanded to include referrals by GPs, which required complying with strict NHS data protection requirements, as well as building integrations with clinical systems used in surgeries and hospitals.
In parallel, to manage the process of clients attending activities, we created a case management system/CRM. To help decision-makers in health and social care analyse the effectiveness of these activities, we created an insights application.
How many people from the vendor's team worked with you, and what were their positions?
Circle Square provided the Ruby on Rails developer that undertook the majority of software development on the project. However, when .Net and other expertise was required for limited time periods, Circle Square were able to pull in relevant resource at short notice. Our CEO was managing the project very closely and remained in constant contact with the management team at Circle Square.
Can you share any measurable outcomes of the project or general feedback about the deliverables?
The marketplace MVP was completed within the expected timeframe and within the fixed quote agreed at the outset. After completion of the MVP, it was more difficult to agree on a clear and fixed scope, so we moved to a retainer engagement. During the course of our two years working with Circle Square, apart from the completion of MVP, they have also helped us develop a case management system/CRM, an insights app and to achieve integration with NHS APIs.
Describe their project management style, including communication tools and timeliness.
Over the course of our work with Circle Square we worked with two Ruby on Rails developers, both of whom were fluent in English and were able to communicate well with the team on our side. They coordinated the testing process with the QA engineer, produced regular demos and always responded promptly to all members of the team.
What did you find most impressive or unique about this company?
Whenever we approached Circle Square, the team aimed to find solutions to our problem as quickly as possible, whether through advice or bringing additional resource on board. They had an understanding of how start-ups work, both from a product and a financial standpoint and were supportive throughout our engagement. They helped us to get a lot done on our growth path.
Are there any areas for improvement or something they could have done differently?
When the RoR developer who completed our MVP decided to leave, Circle Square replaced him with someone else who was evidently too junior for the project. Having realised this, they apologised and asked for a little more time to allocate a suitable person. Shortly after they put forward another developer, who quickly picked up the project and proved to be a great asset to the team.
the project
Marketing Compliance Automation Software for IoT Company
"Circle Square understood our goals immediately and didn't try to upsell us or extend the timelines."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
I was a GM at a major transportation IoT company operating globally.
For what projects/services did your company hire Circle Square, and what were your goals?
We hired Circle Square to develop a short-term compliance solution that checked outgoing communications against a list of potential violations. Our goal was to rapidly develop a tool that would provide intermediate compliance coverage while our own engineers built a more permanent solution.
How did you select this vendor and what were the deciding factors?
I was referred to them by a friend who used them before. The main factors we made our decision based on were: a) track record of truly rapid development and quick iteration, and b) low cost.
Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.
Scope of work was to design, develop and deploy a compliance automation tool that would be used across our marketing team’s workflows. It involved several key components:
- a UI that would allow a user to input data including
- type of message (eg. Text, email, etc),
- size of audience
- geographic location
- the message itself;
- a back-end engine that would test the input content against a variety of content, depending on the input criteria.
For example, text messages would be tested against SMS character length limits, words or word combinations that could put the company at legal risk, spelling and grammar rules, use of dollar signs, and more. It included an output that flagged potential violations and an overall friendly user interface that would make it seamless for our marketing team to run the content through it as part of their workflow.
Lastly, it involved the deployment of the tool for our (non-tech) team to use. It was a Heroku app built on Python in the back-end. Can’t remember what they used for the front end.
How many people from the vendor's team worked with you, and what were their positions?
We worked with a PM, a back-end engineer, and a front-end engineer.
Can you share any measurable outcomes of the project or general feedback about the deliverables?
Our most important metric was the speed of deployment because we needed an immediate stop-gap solution. They built a working product in a total of 3 weeks which was faster than the timeline we shared with leadership. They iterated on it over the following couple of weeks in response to user feedback and got to a high-fidelity tool that our team ended up using for a long time.
Describe their project management style, including communication tools and timeliness.
We worked through their PM who managed the engineers. He arranged calls with them as needed and kept us updated through a shared project tracker. They said they’d get us an MVP in 3 weeks and delivered in a timely manner.
What did you find most impressive or unique about this company?
The most important thing was that they immediately understood what we were trying to do. Our goal wasn’t to build a super high fidelity, highly scalable, clean-code tool, but rather an MVP that would provide us sufficient coverage quickest. We spoke to our other dev firms who said they could do the job in 2+ months. Circle Square understood our goals immediately and didn't try to upsell us or extend the timelines. We got what we wanted and on time.
Are there any areas for improvement or something they could have done differently?
Some deadlines for certain features had to push, and they added them on after delivering the MVP. Would have loved a bit clearer communication around features that were delayed but they got us all the P0 features effectively and on time so no real complaints.
the project
Mobile Security App Dev for Computer Software Company
"They were always prepared to work to our requirements and our timelines."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
At the time of our engagement, I was a product manager at a NASDAQ listed company that provides software as a service and products for inbound email security, outbound data loss prevention, social media, mobile devices, digital risk, email encryption, electronic discovery, and email archiving.
For what projects/services did your company hire Circle Square, and what were your goals?
We hired Circle Square to create a pioneering security application, which scans and analyses all incoming SMS messages from unknown numbers in order to identify and block spam messages.
Circle Square helped us integrate the application into Android infrastructure and have also worked on an extension generating application for iOS, to help developers install the application.
How did you select Circle Square and what were the deciding factors?
We had a number of projects with Circle Square, but the main goal of all the projects undertaken was to offer an SMS filtering service across the iOS and Android platforms.
Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.
We sought to create a security application, which scans and analyses all incoming SMS messages from unknown numbers in order to identify and block spam messages. As an initial stage, we created a demo of the application for iOS to understand how it will work and, when we were happy with the outcome, created an SDK for Android.
The Android SDK gave developers that develop their own messaging apps, the tools to add the SMS filtering feature. We then created an equivalent toolkit for iOS.
How many resources from the Circle Square team worked with you, and what were their positions?
We had a number of specific developers that we have worked with across several projects - one for the iOS platform and another for the Android platform. We have been impressed by their level of knowledge, experience and commitment. They were able to get things done within our, sometimes, aggressive timetables.
Can you share any measurable outcomes of the project or general feedback about the deliverables?
All the applications were delivered on time and to the required standard, taking into account all the input from our technical team. This gave us the confidence to continue to work with Circle Square.
Describe their project management style, including communication tools and timeliness.
We were engaging directly with the developers, but either the COO or the CTO were also on the calls, which helped to ensure that there was a complete understanding of our requirements and expectations. The developers had a good command of English and we had no difficulties understanding them either in verbal or in writing.
What did you find most impressive or unique about this company?
They were always prepared to work to our requirements and our timelines. They also frequently proposed creative solutions, which we have not thought about. On a number of occasions the proposed solutions improved efficiency and enhanced the features of the applications.
Are there any areas for improvement or something they could have done differently?
We anticipated that there maybe delays due timezone differentials, but Circle Square addressed this issue quite early on, by rearranging the working hours of the assigned developers, to create a greater overlap with us.
the project
Custom Software Dev for Real Estate Company
"The hard work that we put in at the outset to establish a very detailed scope certainly paid off."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
In 2019, I was a managing director at a US based real estate development and management company, bringing a new, sociable and amenities focused approach to urban living. At the time, the company had about 100 employees and several residential community locations throughout the US.
For what projects/services did your company hire Circle Square, and what were your goals?
As the company was expanding and looking to monitor more and more aspects of what was on offer to residents at each of our locations, we came to the conclusion that we needed a white label integrated residential real estate asset management solution to cover all our specific needs. We hired Circle Square to create this solution as a fixed price project, based on a detailed agreed scope. The goal of the project was to create a bespoke real estate asset management platform that would address the requirements of our unique urban living concept.
How did you select Circle Square and what were the deciding factors?
I became aware of Circle Square through a friend of mine, who had done a personal fixed price/fixed scope project with them previously and was satisfied with the end result. I remember that the options for delivering a similar fixed price/fixed scope projects in the US was fairly limited, so I approached Circle Square for an initial estimate based on the documentation that we had. We then worked closely with their Project Manager to fully define the scope and the various user journeys before finalizing the project price.
Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.
The project involved the creation of a real estate asset management platform, which monitored and optimized not only the collection of rent, but also the use and maintenance of the buildings and communal areas (e.g. washing machines, vending machines, coffee machines etc.). The platform produced graphical outputs that could be analyzed and compared in different periods, which was particularly important for monitoring cashflow and cost efficiency.
How many people from the vendor's team worked with you, and what were their positions?
The team consisted of a project manager, designer, one machine learning developer, one frontend developer, one backend developer and a QA. There was a moment in which additional resource seemed to have been required in order to meet our agreed timetable and they did add another senior developer, who made sure we got there.
Can you share any measurable outcomes of the project or general feedback about the deliverables?
The platform was delivered within the 7 months timetable that we had agreed at the outset. The hard work that we put in at the outset to establish a very detailed scope certainly paid off.
Describe their project management style, including communication tools and timelines.
They were good about making sure everyone is one the same page, had an easily accessible project tracker and gave timely updates. We used a combination of Asana and Zoom to communicate.
What did you find most impressive or unique about this company?
They delivered the project on time and, after the initial scope was completed, were prepared to make the additional changes that we requested. They approached the project in a structured way, making sure that we always knew where we were in the project relative to the initial milestones that we established. The PM was very immersed in the project and was fully aligned with us on the business logic of what we were trying to create, which made a big difference.
Are there any areas for improvement or something they could have done differently?
Nothing that stands out to me.
the project
Dev Projects for Design Firm
"We were impressed with the versatility of Circle Square to support a broad tech stack."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
At the time that I worked with Circle Square Limited, I was a Project Manager at Plato Design Inc, a Y-Combinator sponsored design agency.
Alongside design expertise, we offered our clients support in implementing the design on their websites, platforms and email templates, with emphasis on a pixel perfect approach.
This is the space in which we started to work with Circle Square and I was responsible for managing a large number of work streams and budgets with them, day to day.
For what projects/services did your company hire Circle Square?
Circle Square handled a variety of complex projects for us, implementing designs using different CMS (e.g. Wordpress, Hubspot, Shopify and Webflow) and native HTML5\CSS3 approaches. They were required to handle the whole development cycle starting from initial code writing, testing, delivering, deployment and support.
The projects that were assigned to them were time critical and sometimes had budget restrictions. I know that alongside my work with Circle Square, we engaged one of their React Developers on a long term retainer to develop a proprietary tech platform for us.
What were your goals for this project?
Each project was different, but my main goal was to achieve client satisfaction and to build client loyalty. We wanted to give clients the sense that they can rely on us, as their companies, most of which were startups, continued to grow. Equally, we wanted to build a relationship with a reliable team of software developers that could respond to our needs and the needs of our clients, beyond pure design.
How did you select this vendor?
Circle Square was recommended to us by the CRO of Plato Design, who studied at Oxford with one of the founders. While this certainly helped Circle Square get their foot in the door, because of the short-term nature of our projects and our strong feedback loop, we were able to immediately assess the quality and timeliness of their delivery.
Circle Square was prepared to a juggle a variety of technologies and projects, which made them an ideal one stop shop for the software development requirements of our clients.
Describe the project and the services they provided in detail.
On each project, Circle Square identified the developer that will be the main point of contact for it and made clear that we can contact the CTO and the COO for any material issues. Plato Design has creative directors and clients across the US and, with Circle Square developers based in Kiev, we agreed a sufficient time overlap between their working hours and ours.
However, when urgent requests came in late in the day or if engagement was required over the weekend, the CTO and the COO picked things up and responded promptly. All communication with the Circle Square team was via Slack and email, which proved to be efficient.
What was the team composition?
There would normally be one developer, who is assigned to the project, and a QA with the CTO the supervising. Each project would first be delivered to us for review, with us providing an initial set of comments, and after the comments were addressed by the Circle Square developer, the project was sent to the client.
There would often be multiple feedback loops, especially where the client decided to change something in terms of the design, and Circle Square continued to provide support in these circumstances.
Can you share any information that demonstrates the impact that this project has had on your business?
It is difficult to single out a project which demonstrates the success of our engagement with Circle Square. They supported us on a large number of projects both small and large and helped to ensure that our clients were satisfied with the end product. Even when they were bringing new developers on board, they seamlessly integrated within the broader team and workflow.
How was project management arranged and how effective was it?
The communication between the teams was via Slack, email and occasional conference calls. While we knew that both the COO and the CTO were fluent in English, it was great that the developers also had a good standard of English, which allowed our Creative Directors to communicate with them directly.
Some of our Creative Directors developed particularly strong relationships with certain individual developers at Circle Square and would ask for them to be assigned to their projects.
Despite the time difference, through regular communication, workflow was carefully managed on both sides to make sure that all involved had sufficient time to complete their project tasks.
What did you find most impressive about this company?
We were impressed with the versatility of Circle Square to support a broad tech stack. We also appreciated their communication and responsiveness and their willingness to go the extra mile for the client, which on a few extreme occasions included getting developers to work weekends and after hours in order to deliver to a tight deadline.
Are there any areas for improvement?
While working with us, Circle Square has had to manage delivery of a number of projects, across a range of tech stacks, concurrently and they did not always have the manpower to progress all the projects at once.
However, in the context of their work with us, this is to a large extent understandable in view of the significant fluctuations in our workflow, it’s unpredictability and our budget constraints.
I should add that Circle Square were always transparent on their capacity and kept us up to date on progress, which allowed us to manage client expectations on timing.
the project
iOS MVP Dev for Micro-Podcasting App
"Circle Square was flexible in accommodating any changes to the application after the design was finalized."
the reviewer
the review
The client submitted this review online.
Please describe your company and your position there.
I help startups realize their potential by implementing the ideas of the founders in the most effective way. I was approached by the founders of Yapper LLC with an idea, which they wanted to bring to life through a multifunctional mobile application. I set about finding the right software development partners to help us create the application.
For what projects/services did your company hire Circle Square?
Circle Square was hired to develop a micro-podcasting app, Yapper, which allows users all over the world to create short audio messages (Yapps) tied to a particular location or an immovable item or structure. Any person using the app can see and listen to Yapps left by others in order to benefit from their knowledge and become better informed about their location.
What were your goals for this project?
We wanted to create an esthetically appealing and user-friendly MVP application, which can be used to attract seed investors and be further developed in the future.
How did you select this vendor?
Circle Square was recommended to us by a friend, who had a positive experience of working with the company and I had the impression, from our first conversation with the COO and CTO, that they understood what Yapper was trying to achieve. I asked Circle Square to offer their most cost-effective solution and the quote, which they provided, was considerably more competitive than the quotes provided to us by companies that we approached in the US.
The main cost savings came from a different, serverless, approach, which Circle Square proposed for the MVP. This was a novel approach, which their CTO came up with, and it saved us both time and money.
Describe the project in detail.
We had extensive discussions with the CTO, the designer and the developer at Circle Square at the outset about the project and documented all the development phases in a formal statement of works, which was annexed to a signed service agreement. In particular, we discussed in detail the advantages and disadvantages of a serverless approach to make sure that it was suitable for our needs.
As the project progressed, we had direct contact with the developer and designer at Circle Square and had weekly update calls to monitor progress. The CTO and/or COO were present on most of the initial calls to make sure that the project was progressing smoothly. Once the CTO and COO were comfortable that the project was progressing and their attendance was not required, they stepped away, but remained responsive on email. Regular and clear communication from the team allowed us to keep a close eye on the development process and to provide additional input as the application was coming along.
What was the team composition?
A designer and an iOS developer were assigned to the project, with the designer completing all the designs at the front end. The designer showed real understanding of our aspirations and the functionality that we wanted to include in the MVP and reflected it in his designs. Once the designs were approved, the developer stepped in to develop the application. The COO remained a key point of contact for any administrative or more fundamental issues that came up throughout the project.
Can you share any outcomes from the project that demonstrate progress or success?
The Yapper application was completed within the estimated timeframe with all the features that we requested and is now available for download from App Store. Circle Square was flexible in accommodating any changes to the application after the design was finalized.
How effective was the workflow between your team and theirs?
We were engaging directly with the designer and the developer, which helped accelerate progress and streamlined communication. They both had a good command of English and we had no difficulties understanding them either in verbal or written form. Having said, it was comforting to know that the COO and CTO were always in the background, if any material issues came up.
What did you find most impressive about this company?
Circle Square were consistent and committed in their engagement with us, going the extra mile to deliver the product that we were seeking and to meet our expectations. In particular, with Apple introducing additional requirements for the admission of the application to App Store, Circle Square undertook the analysis required to address these requirements, guided us on any information, which had to be provided, and implemented the necessary additional changes at their own cost. I should also mention Aleksei, the developer who was assigned to the project and who was exceptionally knowledgeable in iOS. We hope to be able to continue to work with him, once we raise additional funds to develop the app further.
Are there any areas for improvement?
When it came to implementing the changes required for App Store approval, the process took a little longer, but that was understandable, because this was unexpected. We appreciate that Aleksei found the time to make the fairly substantial changes required to meet App Store requirements and upload the application.
Circle Square completed the project within the expected timeframe and budget provided. Throughout the engagement, they had an effective workflow and regular communication with the client. Moreover, the dedicated team went above and beyond to help the client carry out their plans and strategies.