How to protect your SMS API from Bot Attack!

Do you ever wonder how safe APIs are? And are they safe from the world of cyber threats? 

As with everything on the World Wide Web, APIs are not immune to external threats, and thus measures have to be taken to mitigate these issues effectively. The various forms of threats can range from MITM and API injections like XSS & SQLi, to DDoS attacks. A fact that also has to be considered is that each attack has its distinct nature. 

Bots have evolved with the internet as well, and they can create a lot of nuisance from hacking to even denying data access to credible users.

APIs need to implement a different approach to stay safe and a step ahead of these bots. Some of these are discussed as follows:

Geo- Protection

Restrictions that block access of entire countries will provide the service providers with the liberty to choose the geographical extent of the target, making it more effective and less susceptible to bots from various sources. It further empowers the choice of providing or denying access based on numerous criteria like Country code or referrer domain.

Block the outdated user agents/browsers

It is not widely influential, although some contingency can be achieved. Most of the current browsers have implemented a step to stay inactive unless the user updates the software. This is to curb the risks from the string lists attached with the default configurations in outdated agents.

Block the known threats

Known proxy sites could be the threat you might not have seen coming. Assuming that the bots are implementing higher technology can be an ignorant move. Denying access to these known proxy sites might not be very impactful but will surely discourage bots from coming after you through these portals.

We identify and block the known proxy sites and even enable you to report any when identified.

Integration using Token in OTP Widget by setting Throttle Limit will help to prevent Bot attack

For instructions, please refer to this guide:

Throttle Limit Implementation (Rate limits)

Implement rate limiting mechanisms to restrict the number of API requests from a particular source within a specified time frame. This prevents excessive API calls from bots or malicious actors.

To know more about the token, please refer:


Implementing a Re-captcha can serve as an excellent method to deter bots, and it is not only a cost-free service but also user-friendly for the average human user. In fact, it can even be an enjoyable experience for some, resembling a puzzle. Once the login process is safeguarded, it is essential to monitor the number of login attempts, particularly originating from the same IP address.

You have the option to decide the threshold for failed attempts from a specific IP address, at which point the IP address will be blocked. By integrating CAPTCHA or reCAPTCHA into your website or application, you can effectively distinguish between human users and bots.

Monitoring and Logging

Monitor API usage and log requests, including IP addresses, user agents, timestamps, and request payloads. Analyze logs regularly to identify any unusual patterns or suspicious activities that might indicate a bot attack.

Regularly update software

Keep all software and plugins up to date, as outdated versions may contain vulnerabilities exploited by bots.


With a lead and expertise in the transactional SMS biz, MSG91 has stood out to you, owing to its many great features, and security concerns are just one of them. Bots can be annoying, especially when you're trying to put your best step forward, and we ensure that you do so in the most secure way possible.

By implementing these measures, you can significantly enhance the security and resilience of your SMS APIs against bot attacks.

Please Note: MSG91 holds no liability to refund or credit any lost amount in the event of BOT Attacks.