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Fill
The fill step sets an input, textarea, or content-editable field to a value in one operation. It is the fastest way to populate a form, and the place where run inputs and secrets are injected.
In a workflow, this is a step object with "type": "fill". Steps run in order, and each step can read the outputs of the steps before it. See the full workflows reference for the 30+ step types.
Writ runs on your own accounts, with your own credentials and data, on sites you are authorized to use.
Fields
| Field | Type | Description |
|---|---|---|
selector required | selector | The input to fill. |
value required | string | The value. Placeholders resolve at run time: {{key}} from the workflow’s declared inputs, {{vault:name}} for secrets, {{file:slot}} for file assets. |
Example
A single fill step as it appears in a workflow's steps array:
{
"type": "fill",
"config": { "selector": "input[name='email']", "value": "{{email}}" }
}How it behaves
- Secrets are never a step of their own: reference
{{vault:name}}inside a fill value and the secret resolves at run time, outside the recipe. - Use type instead of fill when a field reacts to each keystroke (autocomplete, masked inputs).
Where it runs
The fill step executes wherever the run executes. On your local or BYO agent there is no compute charge and the agent can reach intranet-only systems; on Writ cloud the run is metered by running time (~$0.12 per browser-hour, from your plan’s included usage wallet.
What next
- Workflows - the full step vocabulary and the workflow object.
- Recorder - capture steps by clicking through a site.
- Managed endpoints - turn the workflow into a REST endpoint, or an MCP tool.