Since 2024, many web-based chat applications has played a key role in digital interaction. Privacy and security are the main concern while sharing any information over a public network through web-based applications. This work, investigates the necessary enhancement of security, the vulnerabilities in existing chat platforms that jeopardize user privacy and confidentiality. To improve the chat applications, end-to-end encryption is required to protect user data from potential threats. Hence, a new approach to chat application design is introduced, utilizing advanced encryption technologies such as the Elliptic Curve Diffie-Hellman (ECDH) algorithm, the Hash-based Key Derivation Function (HKDF) with SHA-256 hashing along with AES-256 Ciphertext FeedBack (CFB) for message encryption and decryption. The chat application includes details of user registration, Key generation phase using ECDH, and an encryption-decryption mechanism. Moreover, the practical implementation demonstrates the application’s effectiveness in countering various cyber-attacks. Finally, comparative analysis of the secure chat application against leading chat platforms reveals its advantages in encryption standards and security features.