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CSV Left Join By Key
x402
CSV Left Join By Key is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).
Performs a SQL-style left join of two CSV tables on a specified key column, returning the merged result as deterministic versioned JSON with row counts and normalized values.
Price / call$0.001
Success—
StatusUnknown
How this service works
CSV Left Join By Key: CSV Left Join By Key left-joins two bounded CSV tables on one key column from bounded caller-supplied values without an external provider. Call CSV Left Join By Key before an agent hands structured data or a batch plan to a downstream tool with a stricter contract. Returns the bounded transformation or validation finding with counts, normalized values, and a versioned result contract for CSV Left Join By Key as versioned deterministic JSON. Price: $0.001 USDC via x402 on B…
Output
A versioned deterministic JSON object containing the left-joined rows from both CSV tables, normalized column values, row counts (total left rows, matched rows, unmatched rows), and a versioned result contract describing the output schema.
Example use cases
Enrich orders with customer details
“I have two CSVs: one with order records and one with customer profiles. Can you left join them on 'customer_id' so every order row gets the matching customer name and email appended?”
Match product catalog with inventory data
“Join my product catalog CSV with my inventory CSV on the 'sku' column — I want to keep all products even if they have no inventory entry yet.”
Combine survey responses with participant metadata
“I've got a survey responses CSV and a participants CSV. Left join them on 'participant_id' so I can see each response alongside the participant's demographic info, keeping all responses even if the participant record is missing.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/csv-left-join-by-keyWhen to prefer
Use this endpoint when you need to merge two in-memory CSV datasets relationally without spinning up a database or external data processing service. It is ideal when both tables fit within the 8KB input limit, you need a left join (preserving all left-table rows), and you want a fast, deterministic, versioned JSON result you can pass directly to a downstream tool. Prefer this over generic CSV utilities when you need row counts and a normalized result contract included automatically.
Side effects
- Key column not found in one or both CSVs — returns validation error with column name details
- Malformed or unparseable CSV input — returns parse error with row/column location
- CSV input exceeds 8192-character limit — returns size exceeded error
- Mismatched column types for the key column — may result in zero matches with count of 0
- Empty left CSV — returns empty result with zero rows
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| key | string | Key supplied to CSV Left Join By Key; used only for this bounded calculation and processed in memory without retention. |
| left | string | Left supplied to CSV Left Join By Key; used only for this bounded calculation and processed in memory without retention. |
| right | string | Right supplied to CSV Left Join By Key; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"csv": "id,name,score\n1,Ada,10\n2,Lin,",
"row_count": 2
},
"schema": "delx/util-csv-left-join-by-key/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "fc7b0105dea0cd7ff481614e8ba999b4ca60e2975a5ef301fc7efdbece9ea9cc",
"external_calls": 0
},
"operation": "data_batch:csv_left_join_by_key"
}
}Tags
x402
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