Ensuring secure and private digital communication is crucial due to increasing threats like data breaches and unauthorized access. We propose a secure end-to-end encrypted chat application using Diffie–Hellman Key Exchange and AES-256 within a microservice architecture. Our system leverages Diffie–Hellman for secure key exchange and AES-256 for efficient symmetric encryption. The microservice architecture ensures scalability and modularity, reducing single points of failure. Tests confirm secure communication with low latency and high throughput. The key exchange process generates an identical shared key in real-time without transmitting a private key, ensuring encryption integrity. Messages are encrypted before transmission and can only be decrypted by the intended users, maintaining confidentiality. This approach offers a robust and scalable solution for secure messaging systems.