Financial API JSON to Parquet: Typed Columns, No Code

For analysis, Parquet beats a pile of JSON files: it is smaller, typed and quick to read. Here is how to get there from an API response.

Open the API Response to Table

Use API Response to Table to call the endpoint or paste the JSON, check the columns, and download Parquet. Nested fields are flattened into columns named by their path, and a list of records becomes the rows.

Because Parquet keeps a type for each column, fix the types first. Amounts should be numbers, dates should be dates and ids should be text. If dates arrive as strings, use Data Transformation to change the data type or date format before you export. A column that mixes numbers and text will not behave as a number, so look for stray values with the Data Profiler.

Parquet files are usually far smaller than the same data as JSON or CSV, and tools such as pandas, DuckDB and Spark read them directly. To check the result, convert the Parquet back to CSV with the Format Converter and compare the first and last rows with the source response.

Only GET requests over https work, and an API that blocks browser calls is refused. Use a read-only key. Nothing is uploaded to Data Utility.

Open the API Response to Table

Related tool pages

  • JSON API Response to CSV: Turn the JSON from an API into a CSV file. Nested fields become columns and you pick which list to use. Free, in your browser, with an optional token.

How to use the API Response to Table: step by step

  1. Open API Response to Table and load the response.
  2. Check the columns.
  3. Fix dates and numbers in Data Transformation if needed.
  4. Download Parquet and read it back to check.

When to use the API Response to Table

  • Build an analysis dataset from an API
  • Store snapshots in a compact file
  • Load data into DuckDB or pandas
  • Reduce storage for archived responses

Example

Input: GET https://api.example.com/users + Bearer token

Output: id,name,address.city 1,Ada,London

Frequently asked questions

How does the token work?

Choose Bearer token, API key in a header, or username and password, and paste the value. It is sent only to the API you call, kept in memory, and never saved or written to Data Lineage.

What if the API blocks the request?

Some APIs do not allow calls from other websites (CORS), so the browser blocks the request. Use an API that allows browser access, or ask its owner to enable CORS.

What happens to nested fields?

Nested objects are flattened into columns such as address.city. If the response has several lists, you can choose which one becomes the table.

Is it safe to use a token in API Response to Table?

Your token goes only to the API you call, straight from your browser. Data Utility never receives it or the response. It is kept in memory for that request, not saved, and not written to Data Lineage. Use a token with read-only access when you can.

Tip: Set date and number types before export. Parquet keeps the type you give it.