Tools Reference
Loom has 13 tools. Each page lists the tool's sockets, options and examples.
Studio's palette shows a short name for each tool. The name in parentheses is the tool's type name, which you will see in workflow files, exported code, the AI assistant and the API.
Connect
Load and save data.
| Tool | Type name | Purpose |
|---|---|---|
| Read | Input | Load data from files or databases |
| Write | Output | Save data to files |
Compute
Clean and transform rows and columns.
| Tool | Type name | Purpose |
|---|---|---|
| Filter | Filter | Split rows by a condition (visual builder or expression) |
| Schema | Select | Choose, rename, reorder and cast columns |
| Sort | Sort | Order rows by column values |
| Calculate | Formula | Create or replace columns (50+ built-in operations) |
| Sample | Sample | Take a subset of rows (first N, random and more) |
| Unique | Unique | Split unique rows from duplicates |
Reshape
Summarize data and change its shape.
| Tool | Type name | Purpose |
|---|---|---|
| Aggregate | Summarize | Group rows and calculate totals, counts and more |
| Pivot | Pivot | Turn long data into wide data |
| Unpivot | Unpivot | Turn wide data into long data |
Combine
Merge datasets.
| Tool | Type name | Purpose |
|---|---|---|
| Concatenate | Union | Stack datasets on top of each other |
| Join | Join | Match rows on key columns |
Which tool do I need?
| I want to... | Use |
|---|---|
| Load a CSV, Parquet or Excel file | Read |
| Query a database | Read with a database source |
| Save results | Write |
| Keep only certain rows | Filter |
| Remove, rename or retype columns | Schema |
| Order my data | Sort |
| Calculate a new column | Calculate |
| Take a sample | Sample |
| Find or remove duplicates | Unique |
| Total, count or average by group | Aggregate |
| Turn long data into wide data | Pivot |
| Turn wide data into long data | Unpivot |
| Stack two tables | Concatenate |
| Match rows between two tables | Join |
Common concepts
Sockets
Every tool has sockets. Inputs are on the left and outputs are on the right. Some tools have several sockets, labelled with a letter such as T and F, or L, J and R. See Wiring.
Blocking tools
Sort, Join, Aggregate, Pivot and Unique show a warning triangle in Studio. Unpivot streams its input. Blocking operations must read all their input before they produce output. The Server caches these results. See Performance and Caching.
Configuration
Select a tool to configure it in the left pane. Changes apply immediately. See Configuration Panel.
Expressions
Filter and Calculate accept Polars expressions in Custom mode. See Expressions.
Lazy evaluation
Tools build a Polars query plan. Nothing runs until you preview a socket or run the workflow.