--- title: "Limit Route" url: "https://help.flows.world/en/article/limit-route" language: "en" last_updated: "2026-09-19T06:55:19.403Z" --- # Limit Route ## Overview Limit route lets a flow pass through this point only once per time window you choose. After a run takes the Pass path, the route is locked for the duration you set; any run that arrives before the window ends takes the Fail path instead. Use it for rate limiting, cooldowns, deduplication, and throttling expensive actions. ![](https://cdn-assets.productfruits.com/02c3bec9-6d79-4e9f-bc8b-75c2c7735b52) **Where to find it:** *Flow Control* in the stage library. ## When to Use - Prevent duplicate actions within a time window - Rate limit per user, per request, or per any other entity - Throttle expensive operations, such as API calls or emails - Enforce a cooldown period between actions - Protect against rapid, repeated executions or accidental spam - Debounce a flow that's triggered repeatedly in quick succession ## Configuration ### Required Fields | Field | Description | Example | | --- | --- | --- | | **Time in Seconds** | How long the route stays locked after a run takes the Pass path | `3600` (1 hour), `300` (5 minutes) | ### Optional Fields - **Limit Name** (Advanced): A custom identifier for this lock. If left blank, it defaults to a name based on the stage and flow. Use the same Limit Name across different flows to share one limit between them. Can include `{{variables}}` for per-user or per-entity limits, e.g. `email_sent_{{userId}}`. - **Comment:** Documentation only, no effect on how the stage runs. **Using functions in these fields:** Any value field above accepts `@` functions, for example `@NowSecond` for the current time or `@calc(...)` for a calculation.  See [Flows Functions](https://help.flows.world/en/article/flows-functions) for the full list. ## Exit Points | Exit | When | | --- | --- | | **Pass** | No lock is currently active (first run, or the previous window has expired). A new lock is created. | | **Fail** | A lock is already active. The run takes Fail **immediately** - it does not wait or queue for the window to end and then pass. Route to alternative handling or a message for the user. If you want a delayed retry, send the Fail path to Run Later or Wait a while yourself. | ## How It Works When executed, the stage: 1. **Resolves the Limit Name** - Uses your custom name if provided, otherwise a name based on the stage and flow, always scoped to your workspace 2. **Checks and creates the lock in one step** - So two runs that arrive at almost the same instant can't both slip through; only one of them takes the Pass path 3. **Routes based on the result** - No lock existed: takes Pass and creates a new one. A lock already existed: takes Fail 4. **Lets the lock expire automatically** - After the Time in Seconds you set, the next run after that takes Pass again **Rate limiting model:** Sliding window. The window restarts every time a run takes the Pass path, it isn't tied to a fixed clock time like the top of the hour. ## Examples ### 1\. Prevent Duplicate Email Sends - Limit Name: `email_sent_{{userId}}` - Time in Seconds: `3600` (1 hour) - Pass path: Send Email → End - Fail path: End (skip the email) - **Result:** At most one email per hour per user ### 2\. API Rate Limiting - Limit Name: `api_call_limit` - Time in Seconds: `6` (enforces roughly 10 calls per minute) - Pass path: Call API → continue - Fail path: return an error message - **Result:** At least 6 seconds between calls ### 3\. User Action Cooldown - Limit Name: `reward_claimed_{{userId}}` - Time in Seconds: `86400` (24 hours) - Pass path: save the reward - Fail path: return "Already claimed today" - **Result:** One reward claim per day per user ### 4\. Shared Limit Across Flows - Limit Name: `notification_limit_{{userId}}` (used the same way in every flow) - Time in Seconds: `3600` - Flows: order confirmations, marketing, system alerts - **Result:** All three flows share one limit and coordinate automatically ### 5\. Debouncing Rapid Triggers - Limit Name: `file_process_{{fileId}}` - Time in Seconds: `30` - Pass path: process the file - Fail path: ignore the rapid change - **Result:** The file is processed at most once every 30 seconds, no matter how often it changes ## Key Behaviors | Feature | Behavior | | --- | --- | | **Distributed** | ✓ Works across every server behind your workspace; the limit is shared, not per-server | | **Workspace Isolation** | ✓ Limits are scoped to your workspace; other workspaces can't affect or see yours | | **No Race Condition** | ✓ Checking for a lock and creating one happen as a single step, so two simultaneous runs can't both take Pass | | **Blocked Run** | Routes to Fail immediately; it does not wait or queue for the window to end | | **Time Precision** | 1-second precision; sub-second windows aren't supported | | **Window Type** | Sliding: resets from the last Pass, not a fixed clock time | | **Fails Open** | If a technical issue prevents the check, the flow takes the Pass path rather than getting stuck | | **No Output Variables** | The stage doesn't add any data to the flow; it only routes Pass or Fail | ## Best Practices - ✓ Use descriptive Limit Names that make it clear what's being limited - ✓ Include an entity ID in the name for per-user or per-item limits, e.g. `{{userId}}` - ✓ Choose a time window that balances protection with a good user experience - ✓ Always handle the Fail path with a clear message or fallback action - ✓ Reuse the same Limit Name across flows only when you want them to share one limit - ✓ Combine with other controls, such as authentication, for anything security-critical ## Common Mistakes | Mistake | Symptom | Fix | | --- | --- | --- | | Missing variables in the Limit Name | Using `limit_{{userId}}` but userId isn't set yet | Make sure the variable has a value before this stage runs | | Unintended name collision | Two different actions share a limit by accident | Use a specific name that includes context, e.g. `action_entity_id` | | Not handling the Fail path | The flow appears to break when the limit is hit | Always connect the Fail exit to appropriate handling | | Expecting exact timing | Assuming millisecond precision | Work at the second level and add buffer for anything time-sensitive | | Relying on it for security | Treating the limit as a strict guarantee | Combine with database-level constraints for anything critical; this stage can fail open | | Expecting fixed windows | Assuming a "top of the hour" style reset | Remember the window is sliding and resets from the last Pass | ## Troubleshooting | Issue | Common Cause | Fix | | --- | --- | --- | | Limit doesn't seem to apply; always Pass | A temporary technical issue caused the stage to fail open | If this keeps happening, contact your Flows support contact | | Unexpected limit collisions | The same Limit Name is used for two different things | Use a more specific name that includes an entity ID | | Variable not resolving in the Limit Name | The variable was empty or not set yet | Confirm the variable has a value before this stage runs | | Limit resets sooner or later than expected | The sliding window resets from the last Pass, not a fixed clock time | Plan around the last successful run rather than calendar time | ## Edge Cases - **Very short windows:** Minimum is 1 second; sub-second windows aren't supported - **Default Limit Name:** Different stages in the same flow have independent limits; copying a stage to a new flow creates a new limit - **Empty variable in the name:** Results in a name with a gap, e.g. `limit__action`; make sure variables resolve as expected - **Manual reset:** A lock can be cleared early with the Limit route Reset stage; use carefully so it doesn't defeat the purpose of the limit ## Related Stages - [**Reset Limit**](https://help.flows.world/en/article/reset-limit)**:** Manually clear a lock before it expires - [**Route Flow**](https://help.flows.world/en/article/route-flow)**:** Branch based on variable values instead of execution rate - [**Loop**](https://help.flows.world/en/article/loop)**:** Repeat part of a flow, with delays between iterations - [**Run Later**](https://help.flows.world/en/article/run-later)**:** Schedule delayed execution instead of blocking it