Stop Serial Trials, Quota Farming & Perpetual Evaluators
Serial trialers change emails, cookies, and IPs because those are free to change; the laptop underneath stays the same. Sentinel's device counter links trial #2 through #50 back to that hardware — with an invisible check that returns in under 40ms.
What you're up against
Trial resets that never end
New email, cleared cookies, fresh residential-proxy IP — and the free trial starts over. Nothing in a typical signup flow connects attempt #12 to attempt #11, so the reset loop runs for as long as the abuser cares to keep it going.
Quota farming on AI products
When the free tier includes model inference, every farmed account has a direct marginal cost. Scripted signups harvest quota across dozens of accounts, and the bill lands on your inference invoice, not the abuser's.
Competitors who evaluate forever
A rival's team can rotate trial accounts for months — benchmarking features, probing limits, demoing your product to their own prospects — without ever crossing the paywall or showing up as a single named account.
IP limits that proxies walk around
Per-IP signup caps and disposable-email blocklists are exactly the controls residential proxies and inbox aliases were built to defeat. The abuser adapts once; the control is dead permanently.
What Sentinel does for you
- Count how many of your accounts each device has opened — the times-seen counter survives new emails, fresh IPs, and clean browser profiles
- Flag VPNs, residential proxies, and datacenter IPs on brand-new signups before you provision anything
- Catch the antidetect browsers and automation that make scripted trial farming economical
- Get an allow / review / block decision with reason codes, so trial policy stays in your code
- Score every signup in under 40ms — no CAPTCHA, no extra verification step for honest evaluators
recovered by a B2B SaaS in six months after linking perpetual trial resets to the devices behind them
[ Read Full Case Study ]Where the check goes
For trial abuse there is one call site that matters most: the signup endpoint, before you provision a workspace, mint an API key, or grant any quota. If your product meters usage, run the same check wherever quota is granted or reset — that is the moment a farmed account starts costing you money. The verdict arrives before your provisioning logic runs, so a flagged device never gets trial #2.
// Check the device's account count before granting a new trial
const res = await fetch('https://sntlhq.com/v1/evaluate', {
method: 'POST',
headers: {
'Authorization': 'Bearer ' + process.env.SENTINEL_KEY,
'Content-Type': 'application/json'
},
body: JSON.stringify({ token: req.body.sentinel_token })
});
const risk = await res.json();
if (risk.decision === 'block') return res.status(403).json({ error: 'Request rejected' });
if (risk.decision === 'review') flagForReview(risk.reasons);The signals that matter here
The times-seen counter is the whole product here. Serial trialers change everything that is free to change: email address, cookies, IP, browser profile. The hardware underneath is not free to change, so Sentinel keys a per-customer counter to a cross-browser hardware ID — when signup #14 arrives from the same laptop as signups #1 through #13, the counter says so and the high_activity_device reason fires, whatever the form claims. That one number is the difference between stopping trial abuse at scale and playing whack-a-mole with email domains.
Network signals mean different things at signup. A commercial VPN on a paying customer's login is usually privacy hygiene. The same vpn_detected or datacenter_asn reason on a brand-new trial signup is a much stronger prior, because genuine evaluations overwhelmingly start from home and office networks. Sentinel returns the raw network block (network.vpn, network.proxy, network.datacenter, network.residential) so you can be strict with anonymized signups and invisible to everyone else.
Automation artifacts before the quota grant. Farming a free tier only pays if account creation is cheap, which in practice means scripts, emulators, or antidetect browsers. Sentinel surfaces automation_detected, antidetect_browser, and emulator_detected at the signup itself — so the farmed account never receives an API key and never burns a token of inference quota.
A score and a decision, not a black box. Every check returns a risk_score from 0 to 100, a decision of allow, review, or block, and the reasons behind it. That lets you run asymmetric policy: hard-block automated signups, ask review-band devices for a card on file, and keep a competitor's fifth anonymous trial on the shortest leash you offer.
Common questions
End the perpetual free trial
Free tier: 1,000 requests/hour. No card, no expiry. Detects residential proxies, antidetect browsers, and AI bots.