I've been researching two-factor authentication (2FA) solutions that support multi-channel one-time password (OTP) delivery for a project I'm working on. SMS isn't always reliable enough, so I wanted to share my findings and notes in case they help others looking to implement secure authentication.
I've looked into several providers that offer multi-channel OTP, meaning they go beyond just SMS and have reliable options like voice calls, WhatsApp, and email. Here's a summary of what I found:
1. **Twilio Verify** - Supports SMS, Voice, and WhatsApp. Known for solid APIs and rapid prototyping but can get expensive at scale.
2. **MessageBird Verify** - Offers SMS, Voice, WhatsApp, and Email with built-in verification but has less low-level control.
3. **Sinch Verification** - Provides SMS, Voice, WhatsApp, and Flash Call. Strong carrier relationships but less flexible APIs.
4. **Dexatel Verify** - Features SMS, WhatsApp, Voice, and Email with a clear pricing structure but a smaller ecosystem.
From my testing, the biggest factors to consider are fallback logic, retry speeds, and how costs scale as usage increases. I'm hoping to gather insights from anyone looking into these vendors or similar options!
3 Answers
For real-world applications, choosing 2FA/OTP providers that support multiple channels is key. Some solid options include:
- **Twilio Verify**: Offers a wide range, including SMS, email, and voice. Plus, it allows for flexible delivery with TOTP.
- **MSG91**: They have failover options between channels like WhatsApp, SMS, and email.
- **MojoAuth**: This one includes various features such as SMS OTP, email OTP, and even magic links.
- **Plivo/Vonage**: Their API lets you send OTP through SMS, voice calls, and WhatsApp as well.
Remember, relying solely on SMS isn't reliable due to potential network issues, so it's beneficial to have back-up channels to ensure users get their codes consistently!
Thanks for sharing your insights! One thing I’m curious about is how you monitor the success rates of OTP delivery. Do you rely on the providers' dashboards or do you implement your own tracking to catch issues before users face them? I've noticed instances where delivery was slow, which caused users to drop off, making it hard to pinpoint the problem until it’s too late.
Great question! We found out that using only provider dashboards isn't sufficient for deep insights. We added our own tracking around the OTP process, logging data like delivery times and completion rates. This way, we caught issues like slow delivery much earlier.
Actually, it's more about security than just reliability. SMS isn't considered secure due to vulnerabilities like SS7 attacks. If you want higher security, it’s better to use TOTP on devices. That said, many platforms can’t go TOTP-only, which is why they might still be using SMS or other channels for easier user access.
That's a fair point. SMS does have weaknesses but for many services, usability is the trade-off, especially in consumer-facing applications.
Totally agree! The way fallback is handled is crucial. It enhances user experience, especially when SMS delivery fails.