Use when handling external API rate limits (e.g., OpenAI 429s, HubSpot or Stripe rate limits), preventing duplicate work from rapid event bursts (debouncing user actions), spreading load over time, ensuring per-tenant fairness, processing events in batches, limiting concurrent runs of the same opera

Inngest Flow Control Master Inngest flow control mechanisms to manage resources, prevent overloading systems, and ensure application reliability. This skill covers all flow control options with prescriptive guidance on when and how to use each. These skills are focused on TypeScript. For Python or Go, refer to the [Inngest documentation](https://www.inngest.com/llms.txt) for language specific guidance. Core concepts apply across all languages. Quick Decision Guide "Limit how many run at once" → Concurrency "Spread runs over time" → Throttling "Block after N runs in a period" → Rate Limiting "Wait for activity to stop, then run once" → Debounce "Only one run at a time for this key" → Singleton "Process events in groups" → Batching "Some runs are more important" → Priority Concurrency When to use: Limit the number of executing steps (not function runs) to manage computing resources and prevent system overwhelm. Key insight: Concurrency limits active code execution, not function runs. A function waiting on step.sleep() or step.waitForEvent() doesn't count against the limit. Basic Concurrency Concurrency with Keys (Multi tenant) Use key parameter to apply limit per unique value of the key. Account level Shared Limits When to use each: Basic: Protect databases or limit general capacity Keyed: Multi tenant fairness, prevent "noisy neighbor" issues Account level: Share quotas across multiple functions (API limits) Throttling When to use: Control the rate of function starts over time to work around API rate limits or smooth traffic spikes. Key difference from concurrency: Throttling limits function run starts; concurrency limits step execution. Configuration: limit : Functions that can start per period period : Time window (1s to 7d) burst : Extra immediate starts allowed key : Apply limits per unique key value Rate Limiting When to use: Hard limit to prevent abuse or skip excessive duplicate events. Key difference from throttling: Rate limiting discards events; throttling delays them. Use cases: Prevent webhook duplicates Limit expensive operations per user Protection against abuse Debounce When to use: Wait for a series of events to stop arriving before processing the latest one. Perfect for: User input that changes rapidly (search, document editing) Noisy webhook events Ensuring latest data is processed Priority When to use: Execute some function runs ahead of others based on dynamic data. Advanced example: Singleton When to use: Ensure only one instance of a function runs at a time. Skip Mode (Preserve Current Run) Cancel Mode (Use Latest Event) Batching When to use: Process multiple events together for efficiency. Combining Flow Control Example: Fair AI Processing Pro tip: Most production functions benefit from combining 1 3 flow control mechanisms for optimal reliability and performance.

inngest-flow-control