What's the difference between workflow variables and environment variables?

Workflow variables store runtime data (text, numbers, objects, arrays) that blocks can read and modify during execution. They use syntax. Environment variables store sensitive configuration like API keys using {{KEY}} syntax. They never appear in logs and are managed at the workspace or personal level.

What happens if a variable name has spaces or mixed case?

Variable resolution is case-insensitive and ignores spaces. A variable named 'My Counter' can be referenced as or . However, using consistent naming (like camelCase) is recommended.

Variables

Sim has two systems for injecting dynamic values into your workflows: workflow variables for in-run state and environment variables for secrets and configuration.

Variable Syntax at a Glance

Syntax	What it references	Example
`<variable.name>`	Workflow variable	`<variable.counter>`
`<variable.obj.prop>`	Nested property	`<variable.config.retryCount>`
`<blockname.field>`	Block output	`<agent.content>`
`<loop.index>`	Loop iteration (inside loop)	`<loop.currentItem>`
`<parallel.index>`	Parallel instance (inside parallel)	`<parallel.currentItem>`
`{{KEY}}`	Environment variable	`{{OPENAI_API_KEY}}`

Type < in any block text field to open the variable picker and browse available references.

Workflow Variables

Workflow variables are a global store that any block can read or update during execution. They're defined in the Variables panel in the sidebar and support text, numbers, booleans, objects, and arrays.

Key behaviors:

Global scope: Accessible from any block in the workflow
Run-scoped persistence: Changes during a run are visible to subsequent blocks, but each new execution resets variables to their initial values
Nested access: Use dot notation for object properties (<variable.config.timeout>)
Updated via the Variables block: Use the Variables block to modify variable values mid-workflow

Workflow Variables

Full guide on creating, accessing, and updating workflow variables

Environment Variables

Environment variables store sensitive values like API keys, tokens, and configuration that should never appear in logs or be visible in the workflow canvas.

Creating Environment Variables

Go to Settings in your workspace
Open the Secrets tab
Click Add and enter a key-value pair

Personal vs. Workspace

Scope	Visibility	Use case
Workspace	All workspace members	Shared API keys, team configuration
Personal	Only you	Your personal tokens, dev credentials

When both a workspace and personal variable share the same key, the workspace value takes precedence.

Using Environment Variables

Reference them with double curly braces in any block field:

{{API_KEY}}

Environment variable names must start with a letter or underscore and contain only letters, numbers, and underscores (e.g., MY_API_KEY).

Environment Variables vs. Credentials

	Environment Variables	Credentials
Format	Key-value string pairs	OAuth tokens, API keys with provider context
Syntax	`{{KEY}}`	Selected via dropdown in block config
Best for	Custom API keys, configuration values, feature flags	OAuth services (Slack, GitHub, Google), managed connections
Management	Settings → Secrets	Settings → Credentials

Use environment variables when you have a raw API key or config value. Use credentials when connecting to a service that needs OAuth or managed token refresh.

Name Conflicts

If a workflow variable and a block output share the same name, Sim resolves the reference in a fixed priority order: loop and parallel context first, then workflow variables, then environment variables, then block outputs. To avoid confusion, use distinct names for your variables and blocks.

Common Questions

Workflow variables store runtime data (text, numbers, objects, arrays) that blocks can read and modify during execution. They use <variable.name> syntax. Environment variables store sensitive configuration like API keys using {{KEY}} syntax. They never appear in logs and are managed at the workspace or personal level.

Yes. Use the double curly brace syntax {{KEY}} directly in your code. The value is substituted before execution, so the actual secret never appears in logs or outputs.

Create a workspace-scoped environment variable in Settings → Secrets. All workspace members will be able to use it in their workflows via {{KEY}} syntax.

Variable resolution is case-insensitive and ignores spaces. A variable named 'My Counter' can be referenced as <variable.mycounter> or <variable.My Counter>. However, using consistent naming (like camelCase) is recommended.

Yes. You can use {{KEY}} syntax in any text field, including system prompts, to inject environment variable values.

Variables

Workflow Variables

Common Questions

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