How to flatten nested api responses for pipeline normalization
- Step 1Capture the API response payload — Use your API client, curl, or browser dev tools to capture a representative JSON response from the REST or GraphQL endpoint. GraphQL responses have a data wrapper — paste the full response and the tool handles the top-level data key.
- Step 2Flatten and compare across sources — Flatten one response from each API source you are integrating. Compare the flat key sets side by side to identify semantically equivalent fields with different names (e.g. user_email vs contact_emailAddress).
- Step 3Document the field mapping — Use the flattened keys to build your ETL field mapping table — source flat key →’ target schema column. The JSON Key Renamer tool can apply the renaming transformation to the flat JSON before loading.
- Step 4Include in your ETL pipeline as a transformation step — In Python, use a recursive flatten function at the start of each API ingestor. In dbt, use a macro that calls json_extract_scalar() for each flat key. The flat structure you design here becomes the canonical intermediate representation.
Frequently asked questions
How do I handle GraphQL responses where data is wrapped in a data key?+
GraphQL responses always include a top-level data key containing the actual response. Paste the full GraphQL JSON response — the tool detects the data wrapper and can start flattening from one level below, or you can use the key selector to choose data as the root before flattening.
My API response has conditional nesting — sometimes fields exist, sometimes they do not. How is this handled?+
Flat keys that only appear in some records will be absent from those records in the flattened output. When loaded into a DataFrame or warehouse table, these become NaN or NULL values in the corresponding columns. This is correct behavior — the schema should define these as nullable columns.
Is the API response data — including customer records — sent to JAD Apps?+
No. JSON flattening runs entirely in your browser. Production API responses, customer data, and business metrics are never transmitted to JAD Apps servers.
Privacy first
Conversion runs locally in your browser. No file is uploaded — only metadata counters are saved for signed-in dashboard stats.