Backend Software Engineer, F5

Salary not provided

Python

Postgres

Ruby

MySQL

REST API

FastAPI

Pydantic

Mid and Senior level

Dublin

In office Thursdays

1+ day a week in office

Application delivery and security platform

Job no longer available

Application delivery and security platform

1001+ employees

B2BArtificial IntelligenceSecurityMachine LearningSaaS

Job no longer available

Salary not provided

Python

Postgres

Ruby

MySQL

REST API

FastAPI

Pydantic

Mid and Senior level

Dublin

In office Thursdays

1+ day a week in office

1001+ employees

B2BArtificial IntelligenceSecurityMachine LearningSaaS

Company mission

To define and deploy agile data security, threat management, and governance for AI models, apps, and agents.

Job

Company

Role

Who you are

We are growing our team at CalypsoAI and are looking for an ambitious, versatile, and self-driven Backend Software Engineer
At least 3 years experience with server-side languages such as Python or Ruby with a server side framework like FastAPI or equivalent
Database Knowledge Familiarity with database technology such as Postgres, or MySQL
Strong ability to debug and troubleshoot software components
A passion for providing quality software!
Designing, building, and consuming RESTful APIs
Critical thinking & structured problem solving
Debugging complex, multi-service applications
Working as part of a team
Time management
Inter/intra-team communication

What the job involves

You’ll be building, testing, and maintaining backend applications, as we continue to build out our world's first AI security web application, making your role critical for the success of our business
We put a strong focus on collaboration and quality throughout our stack
The work is technically challenging and highly rewarding. Your work will be crucial to the success of our business, and you will have the opportunity to grow your career with us
Build - Design, develop, and maintain scalable back-end applications, sdks, tools
Collaborate - Work alongside other engineers, QA, data science, and product teams to build user-friendly, high-performance software
Quality - Write clean, efficient, and maintainable code while adhering to best practices in software development
Testing and Troubleshooting: Test, troubleshoot, debug, and optimize existing systems for performance and scalability
Architect - Design backend features with focus on best practice architecture and design patterns
Improve - Make suggestions for better solutions to the problems we face
Learn - Grown with the evolving nature of the web and its new features

Our take

Legacy tech company F5 was originally founded in the 90s as a developer of Application Delivery Controllers, providing load balancing for data centres. It now uses its historical expertise in the development of application-layer, security, automation, and multicloud software tools.

F5 has seen a storied evolution, going public in 1999 on the success of its BIG-IP load-balancing hardware. 48 of the 50 Forbes 50 companies now use F5’s hardware, a testament to its success. New leadership in 2017 sparked a fresh chapter for F5, as it launched F5 Labs, an offshoot company dedicated to analysing global threat intelligence data.

To bolster F5 Labs, the company engaged in something of an acquisition spree in 2025, buying 21 companies in that year alone. Many of these were AI observability and cybersecurity software startups, signifying a shift in focus from its legacy hardware products.

Steph

Company Specialist at Welcome to the Jungle

Insights

Top investors

Glassdoor (3.8)

Company

Funding (last 2 of 5 rounds)

Apr 2025

$5m

EARLY VC

Jun 2023

$23m

SERIES A

Total funding: $44.2m

Company HQ

Central Business District, Seattle, WA

Leadership

François Locoh-Donou

(CEO, President & Chairman)

Also a Board Member at Capital One, Co-Founder & Chairman at Cajou Espoir and was the COO at Ciena.

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