Cogniteq, 38 Reviews, Address, Data & More

Top-rated software development company ⭐⭐⭐⭐⭐

Cogniteq is a professional software agency delivering custom solutions for SMBs and enterprises based in Europe, USA, Canada, and Asia. More than 150 Cogniteq software engineers have been contributing to the success of the clients’ products since 2005.

Min project size
$10,000+
Hourly rate
$50 - $99 / hr
Employees
50 - 249
Locations
Warszawa, Poland
Year founded
Founded 2005
Languages

No have been added yet...

Pricing Snapshot

Min. project size $10,000+

Avg. hourly rate $50 - $99 /hr

Rating for cost 4.9 /5

What Clients Have Said

Cogniteq is noted for its competitive pricing and strong value for cost, with clients emphasizing budget alignment and quality outcomes. Projects typically involve 2-5 team members, tailored to client needs, and are delivered on time, often exceeding expectations in communication and collaboration.

This summary is based on verified Clutch reviews.

Most Common Project Size

< $49,999 based on 15 reviews

< $49,999 $50,000 - $199,999 $200,000 - $999,999 > $1,000,000

Need pricing guidance? Learn more about SEO pricing

Select a service to see pricing information

Cogniteq Review Insights

Overall Review Rating

4.9

Quality 4.9
Schedule 4.9
Cost 4.9
Willing to Refer 4.9

Top Mentions

Review Highlights

Efficient Project Management

Clients commend Cogniteq for their efficient project management, utilizing tools like Scrum, Jira, and Confluence to ensure projects are well-organized and on track.
Effective Use of Agile Methodologies

Cogniteq effectively employs agile methodologies, allowing them to adapt to changes and deliver iterative improvements, which clients find beneficial for project success.
Areas for Improvement in English Proficiency

While Cogniteq's technical skills are strong, some clients noted that improving English proficiency among team members could enhance communication further.
High Value for Cost

Clients frequently mention Cogniteq's services as offering good value for cost, noting that their pricing is competitive while maintaining high standards of quality.
Positive Client Relationships

Cogniteq builds strong, positive relationships with their clients, leading to repeat business and long-term collaborations, as clients appreciate their understanding and support.
Proactive and Professional Team

The team at Cogniteq is noted for their proactive approach, professionalism, and dedication to projects. They are described as a reliable and impressive partner by their clients.

Was this helpful?

Cogniteq Reviews

Submit a Review

Mobile App Development
Confidential
Mar. - May 2025

5.0

Quality: 4.5

Schedule: 5.0

Cost: 4.5

Willing to Refer: 4.0

"It was all good."

May 8, 2025

COO, Bloom Future

Kevin Costa

Education
Germany
1-10 Employees
Online Review

Cogniteq provided frontend development services for an educational company's app. The team helped the client develop the alpha version of the app, including the final features and screens.

Cogniteq delivered the project with good quality and advised the client on how to improve their code structure. The team communicated via virtual meetings, email, and messaging apps and was easy to manage and a pleasure to work with. Overall, the team made an effort to understand the client's needs.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the COO of Bloom Future

Describe what your company does in a single sentence.

Bloom Future is an app that helps students find their career paths after high school.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Front-End Development of the Alpha Version

SOLUTION

How did you find Cogniteq?

Online Search

Why did you select Cogniteq over others?

Pricing fit our budget
Great culture fit
Good value for cost

How many teammates from Cogniteq were assigned to this project?

2-5 Employees

Describe the scope of work in detail. Please include a summary of key deliverables.

Cogniteq advised and helped us developing our alpha version.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Cogniteq delivered the final features and screens that were needed in a good quality, advising us where we can imprve our code structure.

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Management was always easy and a pleasure. Changes in contracts and billing were handled easily.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

Everyone was really nice on a personal level and really tried to understand us as a team and project.

Are there any areas for improvement or something Cogniteq could have done differently?

No, it was all good.

RATINGS

5.0

Custom Software Development
Confidential
Jan. 2021 - Oct. 2024

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"Cogniteq delivered quality work on time and responded to modification requests."

Dec 26, 2024

Executive, Simac PHI DATA

Anonymous

Information technology
Brussels, Belgium
11-50 Employees
Online Review
Verified

Cogniteq provided development services for a software company. The team was responsible for developing and delivering key functionalities and structural parts of the client's next-generation platform.

Thanks to Cogniteq's efforts, the client received quality development outcomes. The team provided timely deliverables, quickly addressed modifications or corrections, was friendly and collaborative, and communicated well throughout the engagement. Their professionalism and agility were unique.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am an executive of Simac PHI DATA

Describe what your company does in a single sentence.

We are a trusted advisor, creator and implementer of solutions for the digitisation of business processes taking place in the Smart Edge environment between the operation floor and the IT infrastructure within logistic, transport, industrial, retail, governmental and healthcare organisations.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Co-development of our new generation software platform

SOLUTION

How did you find Cogniteq?

Online Search
Referral
Other

Why did you select Cogniteq over others?

Great culture fit
Good value for cost

How many teammates from Cogniteq were assigned to this project?

1 Employee

Describe the scope of work in detail. Please include a summary of key deliverables.

Cogniteq contributed in creating our next generation software solution platform in developing and delivering key functionalities and structural parts of thsi solution.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Quality of development
Timely delivery
Great response time in case modification or correction were needed
Very correct and friendly cooperation

Cogniteq delivered quality work on time and responded to modification requests.

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Respect for timing and deadlines,
Open and short communication lines
Understanding of our customer's world

What was your primary form of communication with Cogniteq?

Email or Messaging App

What did you find most impressive or unique about this company?

Agility, Eagerness, professionalism, warm relation & cooperation (Feels like One Team)

Are there any areas for improvement or something Cogniteq could have done differently?

RATINGS

5.0

Custom Software Development IT Staff Augmentation Web Development
$200,000 to $999,999
Jan. 2024 - Jan. 2026

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"All is very well organized from their side."

Oct 15, 2024

CTO, DecideAct A/S

Lasse Laursen

Business services
Denmark
1-10 Employees
Online Review
Verified

Cogniteq provides an Angular developer for a strategy execution software company. The developer has taken over the client's existing platform, aiming to improve its continuous development.

Cogniteq's developer has shown impressive skills and proactiveness. Moreover, the entire team at Cogniteq has been well-organized, responsive, and easy to get a hold of, using virtual meetings, emails, and messages to communicate. Overall, the engagement has been a success.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the CTO of DecideAct A/S

Describe what your company does in a single sentence.

Strategy Execution Software

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Find an Angular Developer

SOLUTION

How did you find Cogniteq?

Referral

Why did you select Cogniteq over others?

High ratings
Pricing fit our budget
Good value for cost
Company values aligned

How many teammates from Cogniteq were assigned to this project?

1 Employee

Describe the scope of work in detail. Please include a summary of key deliverables.

Needed a new Angular developer to take over our existing platform and improve / continue development.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Great work done by the developer. Very skilled and proactive.

Describe their project management. Did they deliver items on time? How did they respond to your needs?

All is very well organized from their side.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

Very responsive and always easy to get a hold of if needed.

Are there any areas for improvement or something Cogniteq could have done differently?

No all is fine

RATINGS

5.0

Custom Software Development IoT Development Other Application Development
Less than $10,000
Jan. - Mar. 2024

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"They did a great job."

Oct 7, 2024

Head of Product Development, SaaS Company

Anonymous

Information technology
Germany
11-50 Employees
Online Review
Verified

Cogniteq provided custom software and IoT development services for a SaaS company. The team was tasked with handling a time-critical project with a limited budget and providing consulting support.

Cogniteq delivered high-quality code and development consulting support. The team established effective collaboration with the internal team and maintained clear, regular communication through virtual meetings. Their valuable insights and exceptional project management made them a reliable partner.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the Head of Product Development of an information technology company

Describe what your company does in a single sentence.

SaaS Cloud Platform Product

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

previous knowledge related to our requirements
time critical project with limited budget
added value consultancy needed for best setup of the technical concept

SOLUTION

How did you find Cogniteq?

Online Search
Referral

Why did you select Cogniteq over others?

Close to my geographic location
Pricing fit our budget
Great culture fit

How many teammates from Cogniteq were assigned to this project?

1 Employee

Describe the scope of work in detail. Please include a summary of key deliverables.

confidential

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

high quality coding and development process. Worked very well with our internal team as a virtual extention.

Describe their project management. Did they deliver items on time? How did they respond to your needs?

very detailed and formal project managment with very good regular communicaitons.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

very good communicaiton and cooperation in designing the concept

Are there any areas for improvement or something Cogniteq could have done differently?

They did a great job, highly recommended

RATINGS

5.0

IT Staff Augmentation UX/UI Design
Confidential
Apr. 2024 - Ongoing

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"They delivered on time and were very active in communication."

Sep 9, 2024

CEO, BI Consulting Company

Anonymous

Consulting
Goeteborg, Sweden
1-10 Employees
Online Review
Verified

Cogniteq provides staff augmentation for a BI consulting company. The team creates web page UX/UI designs using Figma and components using Blazor and Microsoft's Fluent UI.

Cogniteq has delivered beautiful designs and matching components. The team delivers on time and showcases proactive communication primarily via virtual meetings, email, and messaging apps. Their quickness and responsiveness have impressed the client, resulting in a positive engagement.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the CEO of a BI consulting company

Describe what your company does in a single sentence.

Business Intelligence Consulting and product development.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Expand internal team with more development resources

SOLUTION

How did you find Cogniteq?

They called us

Why did you select Cogniteq over others?

Company values aligned

How many teammates from Cogniteq were assigned to this project?

2-5 Employees

Describe the scope of work in detail. Please include a summary of key deliverables.

Beautiful UI/UX designs with help of Figma for new web pages.
UI components for these designs created with Blazor and the Microsoft Fluent UI library.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Beautiful designs and matching blazor components.

Describe their project management. Did they deliver items on time? How did they respond to your needs?

They delivered on time and were very active in communication.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

Responsive and fast.

Are there any areas for improvement or something Cogniteq could have done differently?

RATINGS

5.0

Custom Software Development UX/UI Design
Confidential
Sep. 2023 - June 2024

4.0

Quality: 4.0

Schedule: 4.0

Cost: 4.0

Willing to Refer: 4.5

"We were most impressed with their agility."

Jun 26, 2024

Founder, Audio Intelligence Company

Anonymous

Advertising & marketing
Denmark
1-10 Employees
Online Review
Verified

Cogniteq developed an incremental software self-service portal for an audio intelligence company. This included enhancing the UX/UI and improving features based on user stories and business analysis.

Cogniteq delivered a functional system with stellar features in a timely manner. The team followed the Scrum methodology, discussed errors and change requests via Slack, and ensured a quick turnaround on the reported issues. While they could've offered multiple UI options, their agility was superb.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the Founder of an Audio Intelligence Company

Describe what your company does in a single sentence.

Audio sentiment detection, prediction and recommendation

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Build self-service portal
Assist in enhanced UX

SOLUTION

How did you find Cogniteq?

Online Search

Why did you select Cogniteq over others?

Close to my geographic location
Pricing fits our budget
Good value for cost

How many teammates from Cogniteq were assigned to this project?

2-5 Employees

Describe the scope of work in detail. Please include a summary of key deliverables.

Incremental sw dev in 10 week cycles to baseline portal and gradually enhance feature set based on user storys and business analysis

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Features improved / added performing to spec

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Standard scrum adjusted for small scale, scoping priorities and planning docs exchanged, delivery very timely - Errors and CRs reported via Slack etc. - quick turn around

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

We were most impressed with their agility.

Are there any areas for improvement or something Cogniteq could have done differently?

Could have gone an extra mile to offer multiple UI options

RATINGS

4.0

Custom Software Development IT Staff Augmentation
Confidential
Jan. 2023 - Ongoing

5.0

Quality: 5.0

Schedule: 4.0

Cost: 5.0

Willing to Refer: 5.0

"Their work is done on time and of a very high quality."

Mar 15, 2024

Senior Director of Engineering, Nowtilus GmbH

Ronald Wertlen

Advertising & marketing
Berlin, Germany
11-50 Employees
Online Review
Verified

Cogniteq augments the stream processing team of an ad insertion platform provider. They assist the client in developing a VOD stack optimization plan, VOD stack features, and Poseidon stack streaming features.

Cogniteq has helped the client close tickets. Their team produces high-quality work within the agreed-upon deadline. They also impress the client with their friendly, efficient, and unbureaucratic negotiations. Moreover, the team communicates through email, messaging apps, and online meetings.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the Senior Director of Engineering of Nowtilus GmbH.

Describe what your company does in a single sentence.

Develop and operate a cloud-based server-side ad insertion platform.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

Augment our stream processing team

SOLUTION

How did you find Cogniteq?

Email Marketing

Why did you select Cogniteq over others?

High ratings
Close to my geographic location
Pricing fit our budget
Excellent Interview

How many teammates from Cogniteq were assigned to this project?

1 Employee

Describe the scope of work in detail. Please include a summary of key deliverables.

Standard team augmentation, a Cogniteq employee works directly embedded in our team structures as part of our software development team.

VOD stack optimization plan
VOD stack feature development
Poseidon stack streaming feature development

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

Tickets closed

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Cogniteq did not provide any project management on a product level. Project Management was only in terms of HR handling, contract, etc.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

Their work is done on time and of a very high quality. Negotiations were friendly, efficient and unbureaucratic.

Are there any areas for improvement or something Cogniteq could have done differently?

RATINGS

5.0

"End-to-end good experience with this company"

Custom Software Development
$10,000 to $49,999
Dec. 2023 - Mar. 2024

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"Their attitude and skills are impressive."

Feb 16, 2024

Tech Lead, Testhub

Ronald Mkiza Bagenda Nielsen

Software
Oslo, Norway
1-10 Employees
Online Review

Cogniteq has been hired by a recruitment SaaS company to develop an integration with SAP. The team has also stabilized the MVP before moving on to the integration.

Cogniteq has successfully built the SAP integrations, new domains for new customers, and new environments. Although the client handles the project management, the team has delivered on time and communicated effectively through virtual meetings. Overall, they're professional and efficient.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am the Tech Lead of Testhub

Describe what your company does in a single sentence.

Testhub is a software as a service with the purpos to make the world more equal through fair recruitment. We automate the screening process and minimize bias and noise in hiring decisions.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

SAP Intergration
Stabilize MVP

SOLUTION

How did you find Cogniteq?

Online Search
Clutch Site

Why did you select Cogniteq over others?

High ratings
Good value for cost

How many teammates from Cogniteq were assigned to this project?

2-5 Employees

Describe the scope of work in detail. Please include a summary of key deliverables.

Cognitech were hired to develop an integration with SAP. Before this project could be fully started, some stabilizing of the MVP had to be done which they did.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

A fully built SAP integration, new domains for new customers, new develop environments

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Project management was mostly done on our side, yes their delivery were on time

What was your primary form of communication with Cogniteq?

Virtual Meeting

What did you find most impressive or unique about this company?

Their attitude and skills are impressive

Are there any areas for improvement or something Cogniteq could have done differently?

Not currently

RATINGS

5.0

Custom Software Development IT Staff Augmentation Web Development
Confidential
Apr. 2023 - Ongoing

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"They are highly skilled software engineers, able to quickly integrate to our team."

Jan 18, 2024

Director, Nomad Automate

Anonymous

Telecommunications
Vienna, Austria
11-50 Employees
Online Review

Cogniteq has designed and developed a Java REST API using Java for a data-mining company. The team has transformed API architecture into a micro-service and migrated new services and orchestration using Kafka.

Cogniteq has successfully developed the micro-service, all REST API endpoints, and JSON deliverables. The team has a Kanban-style project management, without hard deadlines and satisfactory production pace. They impressively understand the client's business and provide accurate design options.

The client submitted this review online.

BACKGROUND

Please describe your company and position.

I am a Director of Nomad Automate

Describe what your company does in a single sentence.

Nomad Automate (previously BIG Vienna) is a leading network data-mining expert.

OPPORTUNITY / CHALLENGE

What specific goals or objectives did you hire Cogniteq to accomplish?

We required support in Java development to work on our REST API project.

SOLUTION

How did you find Cogniteq?

I was contacted by Cogniteq's sales manager

Why did you select Cogniteq over others?

High ratings
Pricing fit our budget

How many teammates from Cogniteq were assigned to this project?

2-5 Employees

Describe the scope of work in detail. Please include a summary of key deliverables.

Design and development of a REST API.
Architecture of the API, definition and implementation of endpoints, test and documentation.
Transformation of an existing software project towards a micro-service architecture.
Design development, migration of new services and new orchestration using Kafka.

RESULTS & FEEDBACK

What were the measurable outcomes from the project that demonstrate progress or success?

REST API endpoints production and JSON deliverables.
Mirco-service delivery (compiled deliverables).

Describe their project management. Did they deliver items on time? How did they respond to your needs?

Kanban-like project, without hard deadlines but production pace was very satisfactory.

What was your primary form of communication with Cogniteq?

Virtual Meeting
Email or Messaging App

What did you find most impressive or unique about this company?

They are highly skilled software engineers, able to quickly integrate to our team, adapt and understand our business logic, deliver quality code. Software engineers able to provide concise yet accurate analysis of design options and issues troubleshooting.

Are there any areas for improvement or something Cogniteq could have done differently?

So far nothing to comment nor suggest.

RATINGS

5.0

Custom Software Development
$10,000 to $49,999
Apr. - Dec. 2023

5.0

Quality: 5.0

Schedule: 5.0

Cost: 5.0

Willing to Refer: 5.0

"They were impressively fast and easy to work with."

Jan 17, 2024

CEO, InfoSolutions

Alexander Stendahl

Healthcare
Stockholm, Sweden
11-50 Employees
Online Review
Verified

A healthcare IT company hired Cogniteq to provide custom software development services. The team created a product and set up the program according to the client's specifications.

Cogniteq’s work was met with positive acclaim. The team delivered the software within the agreed-upon budget and according to schedule. They maintained communication through virtual meetings, emails, and messaging apps. Cogniteq was remarkably fast and easy to work with.

Showing 21-30 of 38 Reviews

Clutch verification provides an additional layer of data to help you make the right purchasing decision of business services.

Learn More

Verified Client Reviews: 33

Overall Review Rating: 4.9

Source: Clutch

Last Updated: May 8, 2025

Business Entity

Business Entity Name	Cogniteq Sp. z o.o.
Source	Central Statistical Office of Poland
Jurisdiction of Formation	Poland
Date of Formation	January 24, 2022
Status	Active
Last Updated	December 10, 2024
ID	0000948520

Credit Report Results

International Credit Risk Assessment	Low Risk
Source	Creditsafe
Last Updated	December 10, 2024

Learn More About The Clutch Verification Process

Locations (2)

8 Humańska Warszawa, Poland 00-789

50 - 75

Contact Cogniteq

If you’re not seeing exactly what you need here, send this company a custom message. You can talk about your project needs, price, and timeline to get started on your project.

Cogniteq

Top-rated software development company ⭐⭐⭐⭐⭐

2 Languages that we service

2 Locations

Services

Focus

Industries

Clients

Pricing Snapshot

What Clients Have Said

Most Common Project Size

Select a service to see pricing information

Reviews

Cogniteq Review Insights

Overall Review Rating

Top Mentions

Review Highlights

Efficient Project Management

Effective Use of Agile Methodologies

Areas for Improvement in English Proficiency

High Value for Cost

Positive Client Relationships

Proactive and Professional Team

Reviews mentioning:

Cogniteq Reviews

Sort by

Mobile App Development for Educational Co

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Custom Software Development for Software Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Angular Development for Strategy Execution Software Co

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Custom Software & IoT Development for SaaS Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

UX/UI Design Staff Augmentation for BI Consulting Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Custom Software Dev & UX Design for Audio Intelligence Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Staff Aug & Software Dev for Ad Insertion Platform Provider

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

Custom Software Development for Recruitment SaaS Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS

REST API Design & Development for Data-Mining Company

BACKGROUND

OPPORTUNITY / CHALLENGE

SOLUTION

RESULTS & FEEDBACK

RATINGS