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Supplemental data lets cycle admins attach company-owned, per-employee data points to a performance review cycle—context that Windmill doesn’t collect through review forms. Once loaded, that data appears inside calibration as extra axes, table columns, and packet details, so facilitators and committee members can compare reviewees with the full picture in front of them. Common examples of supplemental data:
  • Compensation band
  • Tenure or time in role
  • Sales attainment or other external performance metrics
  • Promotion nominations or flags from another system
Supplemental data is loaded through the Windmill API—there’s no in-app upload form or CSV importer today. See the Supplemental cycle data API reference for endpoint details.

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How supplemental data works

Each review cycle can hold one set of supplemental fields (the definitions) and one set of values per employee (the data). Both are scoped to a single cycle—data loaded into one cycle doesn’t appear in another.
1

Define the fields

A cycle admin defines the cycle’s supplemental fields via the API—for example, a “Level” single-select field and a “Tenure (years)” scale field.
2

Load the values

The admin pushes per-employee values for those fields, matching employees by email or employee ID.
3

Use it in calibration

The data appears automatically in the cycle’s calibrations—in the axis picker, grid, table, reviewee packets, and the AI pre-read report.
There’s nothing to enable: supplemental data is available on every cycle, and any cycle admin can load it.

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Supported field types

Supplemental fields use the same types as review questions:

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Where supplemental data appears in calibration

Supplemental data is read-only everywhere it appears. To change supplemental data, a cycle admin updates it through the API.

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Axis picker and grid

Supplemental fields appear in the calibration axis picker under a Supplemental data group. A field only shows up once it has at least one value for a reviewee in that calibration—defined-but-empty fields stay out of the way. In grid view, you can use a supplemental field as one or both of the grid’s two dimensions. For example, plot overall rating against job level to check that ratings are consistent within each level. Reviewees are bucketed by their supplemental value, and the cells are read-only.

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Table view

Supplemental fields can be added as columns in table view and sorted like any other column. The one exception: multi-select fields can’t be used as a sort column.

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Reviewee packets

When a calibration’s cycle has supplemental data, each reviewee’s packet gains a Supplemental Data tab listing every field and that reviewee’s current value. Reviewees without a value for a field show “No response.”

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Pre-read report

Supplemental values are included in the context Windy uses to generate the calibration pre-read report, so the narrative can reference them. If supplemental fields or values change after the pre-read is generated, the report is marked stale. Facilitators can click Regenerate to refresh it with the latest data.

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Access and visibility

Supplemental data often contains sensitive information, so access is tightly scoped:
Supplemental data is never visible to employees. It isn’t part of the review packet employees receive when reviews are shared, and it’s excluded from every employee-facing surface.
For how this fits into review visibility more broadly, see Who sees what.

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Updating data mid-cycle

Cycle admins can update supplemental data at any time—there’s no lock when calibration starts. Updates follow a few safety rules:
  • Uploads are full replaces. Removing a field deletes its values, and omitting a field when re-uploading an employee’s values deletes that value—so always send each employee’s complete data.
  • Renaming is safe. Changing a field’s label (or an option’s label) keeps existing values. Changing a field’s type deletes its old values, since they no longer fit.
  • Updates are per-employee. Uploading values for some employees leaves everyone else’s values untouched.
  • The pre-read notices. Any change to fields or values marks generated calibration pre-reads as stale so facilitators know to regenerate.

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FAQs

No. Supplemental data is never shown to reviewees—not in their released review, not anywhere else in Windmill. It’s visible only to cycle admins and, inside calibration, to that calibration’s facilitators and committee members.
No. It’s available on every review cycle. You just need to be a cycle admin and have a Windmill API key to load the data.
Not currently. Supplemental data is loaded through the API. Most teams script the upload from their HRIS or data warehouse so it stays in sync.
A supplemental field only appears in a calibration once at least one reviewee in that calibration has a value for it. Check that you’ve uploaded values for employees who are actually in the calibration, and that a later upload didn’t omit the field—each upload fully replaces an employee’s values.
No. Supplemental data is read-only on the calibration board, in packets, and in the table. Only cycle admins can change it, via the API. Facilitators can still adjust ratings from review questions as usual.
The pre-read report is marked stale so facilitators know it no longer reflects the latest data. A facilitator can click Regenerate to rebuild it with the updated values.