Software Sustainability -- Elements of Sustainability for Public Sector Software - Mosaic Enterprise Architecture, Macroservices, and Low-Code -- How could we have known? Anticipating Sustainability Effects of a Software Product -- Software Sustainability: Academic Understanding and Industry Perceptions -- Engineering and Management -- Tailored Design Thinking Approach - A Shortcut for Agile Teams -- Deliberative Technical Debt Management: An Action Research Study -- Blockchain Governance: A Dynamic View -- Framework for creating relevant, accessible, and adoptable KPI models in an Industrial Setting -- Risk exposure and management in software development - a survey of multiple software startups -- Software Startups -- Supporting Entrepreneurship with Hackathons - A Study on Startup Founders Attending Hackathons -- User Experience Practices in Early-Stage Software Startups - An Exploratory Study -- A Study of Factors on Women from the Tech Sector and Entrepreneurship -- Making Internal Software Startups Work: How to Innovate Like a Venture Builder -- Software Platforms and Ecosystems -- The Economic Anatomy of Paid Crowdsourcing -- Power Relations within an Open Source Software Ecosystem -- When Player Communities Revolt Against the Developer: A Study of Pokémon GO and Diablo Immortal -- Continuous Improvement -- Design Principles for a Crowd-based Prototype Validation Platform -- What are critical success factors of DevOps projects? A systematic literature review -- Towards Federated Learning: A Case Study in the Telecommunication Domain. .

This book constitutes the refereed proceedings of the 21th International Conference on Software Business, ICSOB 2021, which was held during December 2-3, 2021. The conference was originally planned to take place in Drammen, Norway, but changed to an online format due to the COVID-19 pandemic. The special theme of ICSOB 2021 was software sustainability. The 13 full papers and 5 short papers presented were carefully reviewed and selected from 39 submissions. They deal with a range of topics including software sustainability, Agile development, DevOps, software startups, prototyping, software ecosystems, crowdsourcing platforms, technical debts, and risk management. .