Detailed Explanation:

Answer: Option 4 — 1, 2, 3 and 4

All four digital platforms mentioned are built on open-source frameworks, making their source code publicly available for transparency, collaboration, and innovation. While Aarogya Setu was initially proprietary, the government later released its source code as open-source in 2020.

✅ Aarogya Setu – Correct: Initially closed-source but was made open-source by the government in May 2020, with code published on GitHub.
✅ CoWIN – Correct: Built using open-source technologies and the government released its source code as open-source in June 2021.
✅ DigiLocker – Correct: Developed on an open-source Digital Locker System platform, enabling secure storage and sharing of documents.
✅ DIKSHA – Correct: Built on the open-source Sunbird platform developed under the EkStep Foundation initiative.

📝 Short Notes: Government Open-Source Digital Platforms

• Aarogya Setu: COVID-19 contact tracing app; source code made public on GitHub in May 2020 for Android and iOS versions
• CoWIN (COVID Vaccine Intelligence Network): Vaccination registration and certificate platform; made open-source in June 2021 to enable global adoption
• DigiLocker: Digital document storage platform under Digital India; uses open-source architecture for secure document issuance and verification
• DIKSHA (Digital Infrastructure for Knowledge Sharing): National teacher platform and learning resource repository; built on Sunbird open-source platform developed by EkStep Foundation
• Benefits of Open-Source: Transparency, security through public scrutiny, cost-effectiveness, customization, and collaborative improvement
• India Stack: These platforms align with India's broader open-source digital public goods approach, enabling scalability and reusability