Runs onWrit CloudDesktopSelf-hosted
On this page
Upload file
The upload step attaches a file to the page — either by setting it on an <input type="file"> directly, or by clicking a trigger and intercepting the file chooser. The file itself is a stored asset, never bytes baked into the recipe.
In a workflow, this is a step object with "type": "upload". 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 file input, or the trigger that opens the chooser. |
file_id | string | Stored-file handle ("file_…") bound to this step (owner runs). |
file_slot | string | Named file slot for shared workflows; each user binds the slot to their own file. |
mode | string | "input" (set on the input element) or "chooser" (click the trigger, intercept the chooser). |
is_multiple | boolean | Whether the target input accepts multiple files. |
Example
A single upload step as it appears in a workflow's steps array:
{
"type": "upload",
"config": { "selector": "input[type='file']", "file_slot": "invoice", "mode": "input" }
}How it behaves
- Shared workflows carry a file slot, not a file: each user binds their own stored file to the slot.
- A file captured earlier by wait_for_download can be reused here via its
{{file:slot}}reference.
Where it runs
The upload 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.