Elasticsearch Bulk Formatter

About this tool

The Elasticsearch Bulk Formatter builds the exact newline-delimited JSON body used by the Elasticsearch and OpenSearch _bulk APIs. Paste a JSON array of objects, choose the bulk action, and the tool emits compact NDJSON: one action/metadata line per document and, for index, create, and update, one source line after it. The output always ends with the required trailing newline.

Worked example

Input documents:

[{"id":"1","title":"hello"},{"id":"2","title":"world"}]

Options: action index, target _index my-index, ID field id.

Output:

{"index":{"_index":"my-index","_id":"1"}}
{"title":"hello"}
{"index":{"_index":"my-index","_id":"2"}}
{"title":"world"}

The final line in the actual output is followed by \n, so it is safe to save directly as an NDJSON file and send with curl --data-binary.

Options

• Documents JSON array — a JSON array of objects. Each object becomes one operation.
• Bulk action — index, create, update, or delete.
• Target _index — written into every metadata line. Leave blank when you plan to POST to /<index>/_bulk and want the URL to supply the index.
• Document ID field — the field whose value becomes _id; that field is removed from the emitted source document. It is required for update and delete and optional for index and create.
• doc_as_upsert — for update, adds "doc_as_upsert": true beside "doc" so missing documents are inserted from the partial document. It is ignored for other actions.

Limits and edge cases

This tool only shapes the request body. It does not connect to a cluster, validate mappings, chunk large files into upload-size batches, or add per-document routing/version metadata. It errors on invalid JSON, a non-array root, an empty array, a non-object item, and an update or delete action without an _id value. Numeric IDs stay numeric in the metadata line; string IDs stay strings.

FAQ