Rejoice is hiring a
AI / ML Research Engineer

AI / ML Research Engineer Discovery, Search and Recommendation

About Rejoice

Rejoice is an early-stage technology startup that is building a Christian audio platform for worship, music, podcasts, and more.

Rejoice is built to advance the Gospel of Jesus Christ, serve the global and local Church, and give families a screen-free place they can truly trust.

The founding team is highly skilled and experienced at building, shipping, and scaling technologies at a global level.

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About the Role

Rejoice is building a redemptive DSP which includes designing a faith-aligned discovery, search, and recommendation system.

Most audio platforms optimise for time on platform. We are optimising for depth, formation, and faithful discovery.

You will help design and build the core systems that power discovery across a growing global catalogue of Christian audio.

This is a technically demanding problem at the intersection of recommendation systems, semantic understanding, and structured knowledge.

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What You Will Work On

1. Content embedding systems that capture theological, semantic, and contextual relationships across audio content
2. A structured knowledge layer connecting content to scripture references, theological themes, artists, churches, and ministries
3. Listening sequence models that learn how people move between worship music, podcasts, and devotional audio
4. Candidate retrieval and ranking pipelines informed by state-of-the-art recommendation research
5. Data integrity systems that detect anomalous listening patterns and protect training data quality
6. Objective functions that go beyond engagement, including completion depth, content diversity, and discovery of new creators
7. Signal-level detection of artificial streaming behaviour as part of the platform's broader integrity architecture

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What Rejoice Is Looking For

1. Strong foundation in machine learning, recommendation systems, or information retrieval
2. Experience with embedding models, vector similarity search, or sequential behaviour modelling
3. Comfort working across multi-modal data including audio metadata, transcripts, user behaviour, and structured knowledge
4. A genuine interest in building systems that are trustworthy, explainable, and resistant to manipulation
5. Experience in complex or high-integrity ML environments is a plus
6. PhD or equivalent research background valued but not required
7. Alignment with the mission of Rejoice and a sincere appreciation for the Christian context in which the platform operates

Most recommendation systems were never designed to understand the richness of the Christian faith.

Building systems that can faithfully represent and surface this structure presents genuinely interesting research and engineering challenges.

If you want to work on serious machine learning problems while contributing to technology that serves the Church and honours Christ, this is a rare opportunity.

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How To Apply

Send a brief note about yourself, what you have built, and why this role interests you to: hello@rejoiceapp.io

No formal cover letter or CV required.