Phone APIs

Best Phone APIs for Developers

A phone API allows developers to validate phone numbers, perform carrier lookups, send SMS messages, and integrate voice calling into their applications without managing telecom infrastructure. These APIs are essential for OTP verification, notifications, and user authentication.

CodeHelper's curated phone API collection includes APIs covering number validation, carrier detection, SMS sending, voice calls, and telecommunications data.

What to look for in a phone API

• E.164 format support: Ensure the API accepts and normalizes numbers in E.164 international format for consistent storage and processing.
• Line type detection: Distinguishing mobile from landline numbers is important for SMS campaigns, as landlines cannot receive text messages.
• Delivery receipts: SMS APIs with delivery webhooks let you confirm whether messages were actually received by the handset.

How to use this API directory

1. Browse the curated list of APIs below.
2. Click any API to visit its documentation.
3. Check the Auth column to understand what credentials you need.

Whether you are building an OTP system or an SMS notification service, this free curated API directory saves you hours of research.