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The history of Rejoose

2010: It all started with Eoptimo

Eoptimo was founded as an IT energy efficiency and reduction consultancy firm, focused on helping Danish companies reduce energy consumption. Over the years, Eoptimo provided consultancy to more than 800 companies, driving over 3,000 energy-saving projects.

By collaborating closely with the Danish Energy Board, Eoptimo became a recognised leader in the field. This also laid the foundation for what would later become the Rejoose energy and carbon database, and the foundation for e.tool.
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2017: The foundation of Rejoose

Rejoose was established as a spinoff from Eoptimo, with the goal of using data to drive IT energy efficiency.
 
The data collection engine and the initial database, which contained 150,000 IT products, were transferred from Eoptimo to Rejoose, laying the groundwork for future innovations.
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2019: The launch of e.tool

Rejoose introduced e.tool, a groundbreaking platform offering insights into IT energy efficiency.
 

By this time, the database had grown to over 500,000 IT products, and Rejoose began attracting customers in Denmark, marking the beginning of its commercial journey.

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2020: Expanding across the Nordics

e.tool expanded its reach to IT resellers throughout the Nordics, significantly broadening Rejoose’s market presence.
 
As the database continued to grow with more IT products and categories, Rejoose became an approved endorser and member of the EU Code of Conduct on Data Center Energy Efficiency, reinforcing its commitment to sustainable IT practices.
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2021: Significant growth and new focus

Rejoose experienced significant growth in its customer base, driven by an increasing demand for carbon data as EU Taxonomy and CSRD regulations came into effect.
 
The product database expanded to approximately 1.5 million items, enriching the data available to customers. Rejoose focsued on evolving its data collection engine to meet the rising need for accurate and comprehensive carbon data. 
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2022: A strategic pivot and new solutions

Rejoose pivoted from offering a reporting tool to providing detailed carbon and energy data on IT products and services.
The launch of e.voice, which delivers carbon data at invoice level, marked a major shift. The first deal was signed just one month after its launch, bringing in numerous new customers and expanding Rejoose’s strategic direction. 
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2023: Major innovations and market expansion

The final version of the e.voice API was launched, enabling customers to go live from day one.
 
Rejoose secured funding from the EU/Danish Innovation Fund to further develop its data collection engine and new platforms.
 
The launch of e.insights and e.hub provided automated carbon data solutions for invoices and advanced data aggregation for reporting. With these innovations, Rejoose began expanding into the Benelux and UKI regions, while the team grew across development, sales, and data quality.
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2024: A transformational year

Rejoose launched the Rejoose Carbon Data Collection Engine and Database v3, containing over 6 million IT products and 900 million data sets, all accessible via API.
 
The launch of the e.product API, which provides data for webshops and quote systems, marked another leap in Rejoose’s evolution. New global partnerships and strategic negotiations positioned Rejoose for continued growth.
 
The team expanded across multiple departments, including development, sales, customer success, marketing, and data quality.
2024 has been a transformative year, with Rejoose setting new industry benchmarks.

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2025: A year of record growth and global scale

 

2025 marked a year of milestones for Rejoose, breaking new records and expanding its global reach.

◊ The Rejoose database surpassed 15 million IT products, driven by new data agreements with global vendors supplying their LCA data directly to Rejoose.

◊ Rejoose achieved a record-breaking month, adding over 1 million products in just 30 days, demonstrating the scalability and maturity of its Carbon Data Collection Engine.

◊ 2025 also saw one of Rejoose’s strategic partners deliver over 1 million e.voices to their clients, showcasing the accelerating adoption of automated, invoice-level carbon transparency across the IT channel.

◊ Rejoose coverage expanded to companies in 108 countries, with the Nordics and the UK maintaining leadership positions, while the US surged to third place, reflecting strong market momentum.

◊ The year continued to strengthen Rejoose’s position as the global market standard for activity-based carbon data, supporting IT suppliers, distributors, and resellers worldwide.



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2026: Expanding data depth and precision

 

Looking ahead, 2026 will be a year of even deeper insights and broader coverage.

◊ The database is projected to exceed 20 million products, further reinforcing Rejoose’s position as the most comprehensive source of IT carbon and energy data.

◊ Rejoose will expand its sustainability framework by integrating TCO Certified, EPEAT, and other recognised certifications to enrich product-level data with broader ESG context.

◊ A new supplier- and customer-specific transportation model will be introduced, enabling more precise carbon calculations that reflect real-world logistics, including options for bulk delivery, land and sea freight, and last-mile EV transport.

◊ These innovations will deliver the next level of accuracy in product lifecycle data, helping partners and customers make even more informed and responsible IT purchasing decisions.