Add Column

Transform

Append a new column whose value is the same on every row. Use it to tag a stream with its source (source = "salesforce-export"), stamp a constant flag, or attach a literal label that downstream nodes can branch on. For per-row computed values, use Formula instead.

Local processing

This transform runs entirely in your browser. No data is sent to external servers.

How it works

Add Column is a streaming transform: each input row is emitted with one extra column appended. The value is a fixed string applied identically to every row — there is no expression evaluation and no access to other column values.

If you need a value derived from other columns (a sum, a concatenation, a conditional), use Formula. Add Column is purely for stamping constants.

If the configured column name is empty, rows pass through unchanged. If the column name already exists on a row, it is overwritten with the configured value.

Input: One tabular data connection. Output: The same rows with the new column appended (or overwritten if the name collided).

Options

Option	Type	Description	Default
columnName	string	Name of the column to append. Empty string disables the transform.	""
value	string	Literal string written into the new column on every row.	""

The value is always a string, even if it parses as a number. Downstream transforms that expect numeric input may need to coerce it (Formula handles cross-type arithmetic transparently for most cases).

Examples

Tag rows with their source

You’re stacking exports from multiple systems and want each row to carry a source label so you can split them later.

Before:

invoice_id	amount	issued_at
INV-2401	1250.00	2025-08-14
INV-2402	480.50	2025-08-15
INV-2403	900.00	2025-08-15

Configuration: column name: source, value: acme-quickbooks.

After:

invoice_id	amount	issued_at	source
INV-2401	1250.00	2025-08-14	acme-quickbooks
INV-2402	480.50	2025-08-15	acme-quickbooks
INV-2403	900.00	2025-08-15	acme-quickbooks

Stamp a static flag for downstream branching

You’re loading a batch of rows that all need a needs_review flag set so a downstream Filter Rows node can pick them up.

Before:

ticket_id	subject
T-1001	Refund request
T-1002	Address change
T-1003	Subscription cancelled

Configuration: column name: needs_review, value: true.

After:

ticket_id	subject	needs_review
T-1001	Refund request	true
T-1002	Address change	true
T-1003	Subscription cancelled	true

Tips and Edge Cases

• The value is always a string, even when it looks numeric. Configuring value: "42" writes the literal string "42", not the number 42. Numeric-only operators downstream (Filter Rows’ greater than, sort comparisons that expect numbers) parse the cell back, so this usually works in practice — but if you need a typed number column, derive it via Formula instead. See apps/web/src/transforms/add-column/logic.ts:41-48.
• Existing columns with the same name are overwritten silently. No warning is raised if columnName collides with an input column — the new value replaces the old one. Use Rename Columns first if you need to preserve the original column under a different name.

Related Transforms

• Formula — append a column whose value is computed per row from a CEL expression.
• Rename Columns — change an existing column’s name without adding a new column.
• Replace Values — rewrite values inside an existing column rather than appending a new one.