Free Tier

Let Users Try Before
They Pay

Add a free trial to any monetised API in seconds — with per-user limits, a global cap, and automatic reset periods. RelAI enforces it transparently. Zero code changes on your server.

Configure Free TierRead the Docs
How it works

Transparent, relay-level enforcement

RelAI checks free tier before the payment layer. Callers with remaining calls get a direct 200. Others see the normal 402 flow.

1

Request arrives

Caller sends a request to your relay endpoint

2

Usage checked

RelAI resolves caller identity and looks up their counter

3

Free or pay?

Free calls left? Request goes through instantly. Limit reached? User sees the normal payment screen.

4

Your server

Receives a plain HTTP request. No payment or free-tier logic to handle

402 Payment Required — extensions.freeTier
{
  "extensions": {
    "freeTier": {
      "perBuyerLimit": 5,
      "globalCap": 500,
      "globalRemaining": 312,
      "resetPeriod": "daily"
    }
  }
}
Features

Everything you need

Per-user limit

Each caller gets their own counter. Set it to 5 and every new visitor gets five free calls before payment kicks in.

Global cap

Optional ceiling across all users combined. Cap total free exposure at 500 calls and everyone moves to paid once the pool is exhausted.

Reset periods

Counters reset never (lifetime), daily, or monthly. Daily resets turn free tier into an ongoing rate-limit rather than a one-time trial.

Zero backend changes

RelAI intercepts calls before your payment layer. Your server receives a plain HTTP request and never sees free-tier logic.

MCP-aware

AI agents browsing your MCP tool list see free tier info in the tool description — calls remaining, global pool, reset period.

Live dashboard stats

See unique users, total free calls used, and global cap progress. Reset individual counters from the UI or via Management API.

Per-endpoint rules

Configure different limits per endpoint path, or use a wildcard * to apply one rule to all endpoints on your API.

Live 402 extension

When the free tier is exhausted, the 402 response includes globalRemaining so clients can explain what happened and guide users to pay.

Practical patterns

Common configurations

Pick a pattern or mix and match across endpoints.

"Try before you pay"

3 free calls per user · one-time, never resets

Every new user gets 3 free calls for life — no account, no commitment. A natural way to let people experience your API before paying.

"Daily free quota"

10 free calls per user · resets every day

10 free calls each day, per user. Great for keeping users engaged daily without giving away unlimited access.

"Controlled beta budget"

Up to 100 free calls per user · 1,000 total across all users

Perfect for a beta launch — generous per-user allowance with a hard ceiling on total exposure. Once the budget is spent, everyone moves to paid.

"Per-endpoint tiers"

Quick lookups: 50 free/day · Heavy compute: paid only

Give users a taste of lightweight features for free, while keeping expensive operations behind a paywall. Best of both worlds.

Ready to add a free trial?

Open your API in the dashboard, go to the Free Tier tab, and click Add. Done in thirty seconds.

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