Retool

Store the key as a secret configuration variableCopy Anchor Link

In Settings → Configuration variables create CONSTAIA_API_KEY, mark it as secret and set it to ck_test_… (and the live value in the production environment, if you use environments). Secret variables can only be used in resource configuration, not in app code.

Create the REST API resourceCopy Anchor Link

In Resources → Create new → REST API:

Every query using this resource carries the header without the key showing up in the app.

ComponentsCopy Anchor Link

Create an app and add:

• fileInput1: a File Input that accepts images and PDF.
• typeSelect: a Select for the expected type.
• analyzeButton: a Button labelled "Analyze".
• fieldsTable: a Table for the extracted fields.
• reasonsTable: a Table for the verdict reasons.

Load the type catalogueCopy Anchor Link

Create the documentTypes query on the Constaia resource: method GET, path document-types?language=en, run automatically. In typeSelect use {{ documentTypes.data.data }} as data, {{ item.type }} as value and {{ item.label }} as label. The endpoint returns the full catalogue, with each type's fields.

Create the analysis queryCopy Anchor Link

Create the analyzeDocument query on the Constaia resource:

With this body:

{{ JSON.stringify({
  file_base64: fileInput1.value[0].base64Data,
  filename: fileInput1.value[0].name,
  options: {
    expect: typeSelect.value,
    language: "en",
    metadata: { reviewer: current_user.email }
  }
}) }}

fileInput1.value is the list of selected files; each one carries its base64 content and its name. Check the exact property names in the component's state inspector, as they can vary between Retool versions. On analyzeButton, add a Click event handler that runs analyzeDocument.

If you work with live keys, turn on the confirmation before running the query: each analysis spends credits.

Show the resultCopy Anchor Link

• A Text with the verdict: {{ analyzeDocument.data?.verdict?.status ?? analyzeDocument.data?.status }}.
• reasonsTable with {{ analyzeDocument.data?.verdict?.reasons ?? [] }} (columns code, severity, message).
• fieldsTable with:

{{ Object.entries(analyzeDocument.data?.fields ?? {}).map(([name, f]) => ({
  field: name,
  value: typeof f.value === "object" ? JSON.stringify(f.value) : f.value,
  confidence: f.confidence,
  validated: f.validated,
})) }}

More in Verdicts. If the query fails, Retool marks it as failed and Constaia's error body (error.code, error.message, error.request_id) shows up in the query result; add a Failure handler that shows a notification. The codes are in Errors.