104 Junior Developers jobs in London

Application Developer

London - hybrid

8 Months+

Inside IR35- Umbrella only

Core Technical Skills:

React Native & Expo:

• Proficient with React Native and Expo open source modules (bare workflow)
• Strong React fundamentals: hooks, context, state management
• React Navigation, app routing JavaScript & TypeScript
• Advanced JavaScript (ES6+) and TypeScript
• Type safety and maintainability for large-scale projects
• Native Platform Integration Swift (iOS) and Kotlin (Android) for custom native modules
• Native module integration in Expo
• React Native projects
• State Management & Storage Redux for complex state management MMKV for high-performance key-value storage

Nice to have skills:

• Architecture & APIs System Design
• Deep expertise in complex React Native architectures and patterns
• Subject matter expert for technical problem-solving and architectural guidance
• Designs solutions for the most challenging technical requirements GraphQL Integration Apollo GraphQL client expertise
• Query optimisation, caching, error handling
• Real-time subscriptions (coming soon)
• Integration Adobe Analytics implementation and mobile tracking
• Adobe Experience Manager (AEM) for content delivery
• Firebase Remote Config for feature configuration CI/CD
• Knowledge of native build processes and optimisation
• Go-to person for complex deployment and build issues
• GitLab CICD experience a plus Deep Technical Requirements
• Expert-level debugging and problem-solving across iOS/Android platforms

All profiles will be reviewed against the required skills and experience. Due to the high number of applications we will only be able to respond to successful applicants in the first instance. We thank you for your interest and the time taken to apply!

We are seeking Mid-Level Application Software Engineers to join our clients growing team where you’ll play a key role in designing and developing cutting-edge software for audio and live performance technology, collaborating with a supportive and dynamic team dedicated to enhancing the live experience for artists and audiences alike.

What You’ll Do

• Develop and maintain desktop applications for audio and live performance environments
li>Work on cross-platform solutions for Embedded Linux, macOS, and iOS
• Collaborate in Agile teams, contributing to sprint planning, code reviews, and CI/CD pipelines
• Build intuitive graphical user interfaces (GUI) with Qt/QtQuick
• Integrate networking features using TCP/IP for seamless device communication
• Support the evolution of products that shape the sound of live performances globally

What We're Looking For

• Strong proficiency in C++ and C#
• Experience with multithreading and complex, concurrent software systems
• Familiarity with cross-platform desktop development (Embedded Linux/macOS/iOS)
• Understanding of Agile methodologies, CI/CD, and version control
• Networking knowledge (TCP/IP)
• Bonus: Experience or interest in Delphi, Flutter, and full-stack development
• Appreciation for audio mixing technology and live streaming
• Interest in hardware/software integration (FPGA/embedded systems)

You’ll Thrive Here If You…

• Are self-motivated, proactive, and eager to solve complex problems
• Communicate effectively and enjoy collaborating in a team
• Bring prior experience in audio technology or related fields (a plus, not a must)

Why Join?

• Innovative Culture: Help develop new products and enhance existing solutions at the forefront of audio technology
• Real-World Impact: Your work will be used by leading audio professionals on stages and in studios around the world
• Career Growth: Structured progression and opportunities to make a tangible impact
• Work-Life Balance: Flexible hours and a hybrid office model
• Collaborative Team: Work alongside passionate engineers dedicated to delivering the best in live audio technology

If you’re excited about shaping the future of live performance technology and want to work with a team that shares your passion for audio and music, apply now!

We are seeking Mid-Level Application Software Engineers to join our clients growing team where you’ll play a key role in designing and developing cutting-edge software for audio and live performance technology, collaborating with a supportive and dynamic team dedicated to enhancing the live experience for artists and audiences alike.

What You’ll Do

• Develop and maintain desktop applications for audio and live performance environments
li>Work on cross-platform solutions for Embedded Linux, macOS, and iOS
• Collaborate in Agile teams, contributing to sprint planning, code reviews, and CI/CD pipelines
• Build intuitive graphical user interfaces (GUI) with Qt/QtQuick
• Integrate networking features using TCP/IP for seamless device communication
• Support the evolution of products that shape the sound of live performances globally

What We're Looking For

• Strong proficiency in C++ and C#
• Experience with multithreading and complex, concurrent software systems
• Familiarity with cross-platform desktop development (Embedded Linux/macOS/iOS)
• Understanding of Agile methodologies, CI/CD, and version control
• Networking knowledge (TCP/IP)
• Bonus: Experience or interest in Delphi, Flutter, and full-stack development
• Appreciation for audio mixing technology and live streaming
• Interest in hardware/software integration (FPGA/embedded systems)

You’ll Thrive Here If You…

• Are self-motivated, proactive, and eager to solve complex problems
• Communicate effectively and enjoy collaborating in a team
• Bring prior experience in audio technology or related fields (a plus, not a must)

Why Join?

• Innovative Culture: Help develop new products and enhance existing solutions at the forefront of audio technology
• Real-World Impact: Your work will be used by leading audio professionals on stages and in studios around the world
• Career Growth: Structured progression and opportunities to make a tangible impact
• Work-Life Balance: Flexible hours and a hybrid office model
• Collaborative Team: Work alongside passionate engineers dedicated to delivering the best in live audio technology

If you’re excited about shaping the future of live performance technology and want to work with a team that shares your passion for audio and music, apply now!

Application Developer

London - hybrid

8 Months+

Inside IR35- Umbrella only

Core Technical Skills:

React Native & Expo:

• Proficient with React Native and Expo open source modules (bare workflow)
• Strong React fundamentals: hooks, context, state management
• React Navigation, app routing JavaScript & TypeScript
• Advanced JavaScript (ES6+) and TypeScript
• Type safety and maintainability for large-scale projects
• Native Platform Integration Swift (iOS) and Kotlin (Android) for custom native modules
• Native module integration in Expo
• React Native projects
• State Management & Storage Redux for complex state management MMKV for high-performance key-value storage

Nice to have skills:

• Architecture & APIs System Design
• Deep expertise in complex React Native architectures and patterns
• Subject matter expert for technical problem-solving and architectural guidance
• Designs solutions for the most challenging technical requirements GraphQL Integration Apollo GraphQL client expertise
• Query optimisation, caching, error handling
• Real-time subscriptions (coming soon)
• Integration Adobe Analytics implementation and mobile tracking
• Adobe Experience Manager (AEM) for content delivery
• Firebase Remote Config for feature configuration CI/CD
• Knowledge of native build processes and optimisation
• Go-to person for complex deployment and build issues
• GitLab CICD experience a plus Deep Technical Requirements
• Expert-level debugging and problem-solving across iOS/Android platforms

All profiles will be reviewed against the required skills and experience. Due to the high number of applications we will only be able to respond to successful applicants in the first instance. We thank you for your interest and the time taken to apply!

Why work for us?
A career at Janus Henderson is more than a job, it's about investing in a brighter future together.
Our Mission at Janus Henderson is to help clients define and achieve superior financial outcomes through differentiated insights, disciplined investments, and world-class service. We will do this by protecting and growing our core business, amplifying our strengths and diversifying where we have the right.
Our Values are key to driving our success, and are at the heart of everything we do:
Clients Come First - Always | Execution Supersedes Intention | Together We Win | Diversity Improves Results | Truth Builds Trust
If our mission, values, and purpose align with your own, we would love to hear from you!
Your opportunity
As Application Developer, you will be responsible for defining and developing business and systems solutions as well as leading ongoing support for existing ones. You will be an integral member of the Product Master IT Team, working closely with business partners, vendors and other IT Product delivery team members to ensure full delivery of the product lifecycle.
+ Research, design, develop, test, debug, document and support custom .NET applications and Data Warehouse solutions in support of the business needs.
+ Partner with the Product Owner, business stakeholders, and IT delivery team members to deliver and support technology solutions.
+ Deliver to time-sensitive product release schedules by collaborating with team members in an agile development environment.
+ Produce technical specifications and release notes for required features and architectural/framework improvements.
+ Provide ongoing change management including training and documentation updates.
+ Collaborate closely with the wider technology teams to coordinate interdependencies, resolve issues, and understand overlaps of teams and applications.
Must have skills
+ Proven experience in the IT field with hands-on experience in system architecture and enterprise data.
+ Proficient with programming languages (C#, ASP.NET.NET Core, SQL).
+ Demonstrated experience in working with REST APIs.
+ Demonstrated experience in working with Cloud data warehouse like Databricks and Snowflake.
+ Demonstrated experience in working with modern cloud data and DevOps techniques.
+ Strong understanding of Agile methodologies with experience working on Agile delivery teams.
+ Exceptional communication skills with the ability to communicate appropriately with both business leadership and technical teams.
+ Fair understanding of Microsoft technology stack. Specifically: C#, Web APIs, SQL Server, Entity Framework, Visual Studio.
+ Understanding of differences between standard and .NET core platform.
Nice to have skills
+ Knowledge of the Asset Management business, preferably in Distribution and Marketing.
+ An enthusiasm for software development and acquiring new skills and knowledge, both in the technology and investments arenas.
+ An exposure to collaboration tools such as Git / Source control, JIRA, Confluence and Teams.
+ UI / front end development skills using web technologies.
What to expect when you join our firm
+ Hybrid working and reasonable accommodations
+ Generous Holiday policies
+ Excellent Health and Wellbeing benefits including corporate membership to ClassPass
+ Paid volunteer time to step away from your desk and into the community
+ Support to grow through professional development courses, tuition/qualification reimbursement and more
+ All-inclusive approach to Diversity, Equity and Inclusion
+ Maternal/paternal leave benefits and family services
+ Complimentary subscription to Headspace - the mindfulness app
+ All employee events including networking opportunities and social activities
+ Lunch allowance for use within our subsidized onsite canteen
Supervisory responsibilities
+ No
Potential for growth
+ Mentoring
+ Leadership development programs
+ Regular training
+ Career development services
+ Continuing education courses
You will be expected to understand the regulatory obligations of the firm, and abide by the regulated entity requirements and JHI policies applicable for your role.
At Janus Henderson Investors we're committed to an inclusive and supportive environment. We believe diversity improves results and we welcome applications from all backgrounds. Don't worry if you don't think you tick every box, we still want to hear from you! We understand everyone has different commitments and while we can't accommodate every flexible working request we're happy to be asked about work flexibility and our hybrid working environment. If you need any reasonable accommodations during our recruitment process, please get in touch and let us know at
LI-LN1 #LI-Hybrid
Janus Henderson (including its subsidiaries) will not maintain existing or sponsor new industry registrations or licenses where not supported by an employee's job functions (as determined by Janus Henderson at its sole discretion).
All applicants must be willing to comply with the provisions of Janus Henderson Investment Advisory Code of Ethics related to personal securities activities and other disclosure and certification requirements, including past political contributions and political activities. Applicants' past political contributions or activity may impact applicants' eligibility for this position. Janus Henderson is an equal opportunity /Affirmative Action employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability or veteran status. All applications are subject to background checks.

**Introduction**
At IBM CIC, we deliver deep technical and industry expertise to a wide range of public and private sector clients in the UK.
A career in IBM CIC means you'll have the opportunity to work with visionaries across multiple industries to improve the hybrid cloud and AI journey for the most innovative and valuable companies in the world. Your ability to accelerate impact and make meaningful change for your clients is enabled by our strategic partner ecosystem and our robust technology platforms across the IBM portfolio.
Curiosity and a constant quest for knowledge serve as the foundation to success here. You'll be encouraged to challenge the norm, investigate ideas outside of your role, and come up with creative solutions which impact a wide network of clients, whom may be at their site or one of our CIC or IBM locations. Our culture of evolution centres on long-term career growth and development opportunities in an environment that embraces your unique skills and experience.
We offer:
* Many training opportunities from classroom to e-learning, mentoring and coaching programs and the chance to gain industry recognized certifications
* Regular and frequent promotion opportunities to ensure you can drive and develop your career with us
* Feedback and checkpoints throughout the year
* Diversity & Inclusion as an essential and authentic component of our culture through our policies and process as well as our Employee Champion teams and support networks
* A culture where your ideas for growth and innovation are always welcome
* Internal recognition programs for peer-to-peer appreciation as well as from manager to employees
* Tools and policies to support your work-life balance from flexible working approaches, sabbatical programs, paid paternity leave, maternity leave and an innovative maternity returners scheme
* More traditional benefits, such as 25 days holiday (in addition to public holidays), online shopping discounts, an Employee Assistance Program, a group personal pension plan of an additional 5% of your base salary paid by us monthly to save for your future.
**Your role and responsibilities**
We're seeking a Managing DevOps Engineer to significantly contribute to our DevOps efforts. In this role, you'll lead projects, guide engineering teams, and shape our technical direction in DevOps practices. You will also actively participate in the entire DevOps lifecycle, focusing on automating and streamlining software delivery pipelines using modern DevOps tools and methodologies.
Responsibilities
* Design, develop, and maintain robust, scalable, and secure DevOps infrastructure and processes using modern tools and methodologies.
* Guide and mentor junior and mid-level engineers, fostering a culture of innovation, quality, and efficiency in DevOps practices.
* Lead the resolution of complex technical challenges, applying your deep expertise in DevOps.
* Drive continuous improvement in our DevOps practices, ensuring alignment with industry standards and best practices.
* Shape the technical direction of our DevOps initiatives and contribute to strategic decision-making
**Required technical and professional expertise**
* Extensive experience in DevOps practices and CI/CD pipeline development.
* Exceptional communication, facilitation, and coaching skills.
* Strong decision-making and problem-solving abilities.
* Ability to influence stakeholders at all levels and drive organizational change.
* Proven experience in leading DevOps initiatives and projects.
As an equal opportunities' employer, we welcome applications from individuals of all backgrounds. However, for you to be eligible for this role, you must have the valid right to work in the UK. Unfortunately, we do not offer visa sponsorship and have no future plans to do so. You must be a resident in the UK and have been living continuously in the UK for the last 10 years. You must be able to hold or gain a UK government security clearance.
**Preferred technical and professional experience**
* Experience with CI/CD tools (e.g., Jenkins, GitLab CI/CD, CircleCI).
* Familiarity with configuration management tools (e.g., Ansible, Puppet, Chef).
* Knowledge of infrastructure as code (IaC) tools (e.g., Terraform, CloudFormation).
* Experience with monitoring and logging tools (e.g., Prometheus, ELK Stack, Datadog).
* Passion for continuous learning and professional development.
IBM is committed to creating a diverse environment and is proud to be an equal-opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, gender, gender identity or expression, sexual orientation, national origin, caste, genetics, pregnancy, disability, neurodivergence, age, veteran status, or other characteristics. IBM is also committed to compliance with all fair employment practices regarding citizenship and immigration status.

Job Title: KDB Specialist/Application Developer

Contract Length: 12 Months

Location: London (Hybrid working model)

Pay Rate: 800 to 1,200 per day (Umbrella)

About the Role:
We are seeking a talented KDB Specialist Developer to join our eFX Strategy & Engineering teams. In this role, you will help build and enhance our analytics framework in KDB+/q , ensuring the resiliency and scalability of our KDB+ estate. You will also be responsible for developing reporting dashboards for key stakeholders, leveraging data stored within KDB.

Key Responsibilities:

• Collaborate with the eFX Strategy and Engineering teams to design and implement robust KDB+/q solutions.
• Enhance the performance, reliability, and resilience of our KDB+ environment.
• Build and maintain reporting dashboards for stakeholders using KDB data.
• Support the analytics framework to meet evolving business needs.

Requirements:

• Strong experience with KDB+/q development and analytics frameworks.
• Previous exposure to eFX or financial markets is a plus.
• Proven ability to design and implement efficient data solutions.
• Excellent problem-solving and communication skills.

Benefits:

• Competitive daily rate (1,200 Umbrella)
• 12-month contract with potential for extension
• Opportunity to work with a leading eFX team on high-impact projects

Please be advised if you haven't heard from us within 48 hours then unfortunately your application has not been successful on this occasion, we may however keep your details on file for any suitable future vacancies and contact you accordingly.

Pontoon/Adecco is an employment consultancy. We put expertise, energy, and enthusiasm into improving everyone's chance of being part of the workplace. We respect and appreciate people of all ethnicities, generations, religious beliefs, sexual orientations, gender identities, and more. We do this by showcasing their talents, skills, and unique experience in an inclusive environment that helps them thrive.

Job Title: KDB Specialist/Application Developer

Contract Length: 12 Months

Location: London (Hybrid working model)

Pay Rate: 800 to 1,200 per day (Umbrella)

About the Role:
We are seeking a talented KDB Specialist Developer to join our eFX Strategy & Engineering teams. In this role, you will help build and enhance our analytics framework in KDB+/q , ensuring the resiliency and scalability of our KDB+ estate. You will also be responsible for developing reporting dashboards for key stakeholders, leveraging data stored within KDB.

Key Responsibilities:

• Collaborate with the eFX Strategy and Engineering teams to design and implement robust KDB+/q solutions.
• Enhance the performance, reliability, and resilience of our KDB+ environment.
• Build and maintain reporting dashboards for stakeholders using KDB data.
• Support the analytics framework to meet evolving business needs.

Requirements:

• Strong experience with KDB+/q development and analytics frameworks.
• Previous exposure to eFX or financial markets is a plus.
• Proven ability to design and implement efficient data solutions.
• Excellent problem-solving and communication skills.

Benefits:

• Competitive daily rate (1,200 Umbrella)
• 12-month contract with potential for extension
• Opportunity to work with a leading eFX team on high-impact projects

Please be advised if you haven't heard from us within 48 hours then unfortunately your application has not been successful on this occasion, we may however keep your details on file for any suitable future vacancies and contact you accordingly.

Pontoon/Adecco is an employment consultancy. We put expertise, energy, and enthusiasm into improving everyone's chance of being part of the workplace. We respect and appreciate people of all ethnicities, generations, religious beliefs, sexual orientations, gender identities, and more. We do this by showcasing their talents, skills, and unique experience in an inclusive environment that helps them thrive.

**Introduction**
At IBM CIC, we deliver deep technical and industry expertise to a wide range of public and private sector clients in the UK.
A career in IBM CIC means you'll have the opportunity to work with visionaries across multiple industries to improve the hybrid cloud and AI journey for the most innovative and valuable companies in the world. Your ability to accelerate impact and make meaningful change for your clients is enabled by our strategic partner ecosystem and our robust technology platforms across the IBM portfolio.
Curiosity and a constant quest for knowledge serve as the foundation to success here. You'll be encouraged to challenge the norm, investigate ideas outside of your role, and come up with creative solutions which impact a wide network of clients, whom may be at their site or one of our CIC or IBM locations. Our culture of evolution centres on long-term career growth and development opportunities in an environment that embraces your unique skills and experience.
We offer:
* Many training opportunities from classroom to e-learning, mentoring and coaching programs and the chance to gain industry recognized certifications
* Regular and frequent promotion opportunities to ensure you can drive and develop your career with us
* Feedback and checkpoints throughout the year
* Diversity & Inclusion as an essential and authentic component of our culture through our policies and process as well as our Employee Champion teams and support networks
* A culture where your ideas for growth and innovation are always welcome
* Internal recognition programs for peer-to-peer appreciation as well as from manager to employees
* Tools and policies to support your work-life balance from flexible working approaches, sabbatical programs, paid paternity leave, maternity leave and an innovative maternity returners scheme
* More traditional benefits, such as 25 days holiday (in addition to public holidays), online shopping discounts, an Employee Assistance Program, a group personal pension plan of an additional 5% of your base salary paid by us monthly to save for your future.
**Your role and responsibilities**
As a Senior Application Developer-Experience Front End, you'll be at the forefront of our digital product development, driving innovation and excellence in front-end engineering. You will be responsible for delivering high-quality frontend solutions by setting the coding standard, shaping the architecture, guiding engineering practices, and lead the team through complex technical challenges in large scale digital transformation projects. As part of a project senior technical leadership team, you will also contribute to stakeholder management and strategic planning at account level.
Responsibilities:
* Lead the frontend development of complex web applications using modern JavaScript libraries and frameworks (React, Next.js, Vue.js etc.).
* Define technical architecture, patterns, and practices for scalable, maintainable, and high-performing frontend solutions.
* Act as technical lead on projects - setting direction, ensuring code quality, and aligning delivery with client needs.
* Mentor and support junior and mid-level developers, promoting a culture of learning, quality, and continuous improvement.
* Collaborate closely with designers, backend developers, DevOps, QA, and other stakeholders to drive end-to-end delivery.
* Collaborate closely with stakeholders to translate business requirements into clear technical design and requirement, and in turn into compelling user experiences.
* Define and lead implementation of development workflows, CI/CD pipelines, testing strategies, and release processes.
* Communicate technical decisions and trade-offs clearly to clients and internal stakeholders.
**Required technical and professional expertise**
* Deep practical experience with modern JavaScript and its libraries and frameworks like React, Next.js, Vue.js or similar.
* Strong understanding of design systems, component libraries, and working closely with UX/UI teams.
* Proven track record in technical leadership roles, leading delivery teams in complex, multi-environment projects.
* Strong understanding of frontend architecture, including performance, security and compliance, accessibility, and scalability considerations.
* Experience defining the implementation of robust testing strategies (unit, integration, E2E) and managing quality in delivery pipelines.
* Strong understanding of DevOps practices and tooling relevant to frontend development.
* Excellent written and verbal communication skills - able to engage with clients, present solutions, and explain technical concepts clearly.
* Experience working in agile, cross-functional teams, with an understanding of effective delivery methodologies.
* Outstanding problem-solving skills and ability to handle multiple tasks concurrently.
As an equal opportunities' employer, we welcome applications from individuals of all backgrounds. However, for you to be eligible for this role, you must have the valid right to work in the UK. Unfortunately, we do not offer visa sponsorship and have no future plans to do so. You must be a resident in the UK and have been living continuously in the UK for the last 10 years. You must be able to hold or gain a UK government security clearance.
**Preferred technical and professional experience**
* Experience in consulting or client-facing roles, ideally in a digital or enterprise environment.
* Familiarity with backend technologies (e.g., Node.js, APIs) and how frontend integrates into broader systems.
* Exposure to cloud-native architectures (e.g., AWS, Azure, serverless, containerized environments).
* Experience contributing to pre-sales and project discovery phases by advising on technical feasibility and shaping solutions.
* Involvement in technical communities or thought leadership (e.g., speaking, blogging, OSS contributions).
IBM is committed to creating a diverse environment and is proud to be an equal-opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, gender, gender identity or expression, sexual orientation, national origin, caste, genetics, pregnancy, disability, neurodivergence, age, veteran status, or other characteristics. IBM is also committed to compliance with all fair employment practices regarding citizenship and immigration status.