How to protect your free trial from abuse
Free trials attract people who sign up over and over. Practical ways to keep the offer generous for real users and unattractive to abusers.
Photo by image4you on Pixabay
A free trial is one of the best ways to sell software, and one of the easiest to exploit. Someone who can create unlimited accounts can use your product for free indefinitely, and at scale, abuse can cost real money.
What abuse looks like
- one person registering many accounts with different addresses
- scripts creating accounts in bulk to farm credits
- trial accounts used to send spam or run heavy workloads
- referral and coupon systems exploited with fake accounts
Start with the email address
Email is the main identity at signup, so it is the first place to add friction:
- Reject disposable domains (how detection works).
- Normalise addresses before comparing. Some providers ignore dots and everything after a
+in the local part, soa.b+1@gmail.comandab@gmail.comcan reach the same inbox. Compare on the normalised form so one person can't claim many "different" accounts. - Verify the mailbox where possible and require confirmation before the trial begins.
Add layers beyond email
- Rate limits on signups per IP and per network.
- A bot challenge or honeypot field.
- Device or browser signals to spot repeat visitors, used carefully and disclosed in your privacy policy.
- A payment method up front, if your market accepts it. This is the strongest deterrent, at the cost of fewer trials.
Limit what a trial can do
- Cap usage so abuse doesn't cost you much.
- Delay or disable anything expensive or risky until the account has been confirmed.
- Don't allow outbound messaging in trials, or throttle it heavily.
- Watch for accounts that spend their entire allowance in minutes.
Design for the honest majority
Most people who sign up are exactly who they appear to be. Keep the path smooth for them:
- explain rejections plainly and offer a way to appeal
- don't make every user solve a puzzle
- make the trial valuable enough that people want to keep one account
Review regularly
Sort new accounts by signup source and look at the share that confirm, activate and convert. Abuse tends to cluster. When a pattern appears, add a rule for it and check you haven't blocked real users. Related reading: stopping fake signups.
