How many beta testers did you grant free access to for your SaaS product?

For use more like a time-based event.

In the absolute initial stage, I will give free access to 5 to 10 close known people in my targeted industry. I will first have a one-to-one call or sit with them as they navigate through the MVP. That is the only way I receive first-hand experience. Those are crucial suggestions. Once we cross that stage, a better strategy with a good sample of BETA testers is required. 50, 100, 200 or even 1000. You can add a fill-out form on your website if a user wants to be a BETA user and want to free access. You can check the details and grant BETA access. That's how you know the background of BETAs and ask for feedback at regular intervals.

I hv been actively thinking of this for the SaaS we are building. Is there any rule of thumb for this?

Oh that's an interesting topic! @imanmoaz what do you think should be the healthy number? Or for how long do you think this free access should be granted?

For me there are a few factors that will influence this, firstly how finished is your Beta / MVP? Is it the first iteration of an end-to-end product? Or is it just one feature / component that is ready to use with more coming? Secondly, is it a self-serve SaaS offering? Or is it something that is going to be complemented with a Customer Success team / etc? Thirdly, how many different beta testers can you effectively service? ie. From support? Feedback? Ideally, if you have an end-to-end beta that is self-serve and you can support a significant number of users, it doesn't hurt to have as large of free beta as possible, just to really collect a lot of data points, validate your assumptions about ideal customers/etc, test how the product is actually working and see what breaks. If however your product is not yet finished end-to-end or you have concerns about scalability / etc, then of course a more targeted approach makes sense.