csvkit

Agentic-first CSV manipulation service. Parse, format, filter, sort, select columns, rename, add/remove columns, transform, deduplicate, transpose, join, split, convert to/from JSON, and analyze CSV data. Plain text API, agent-driven, single Go binary.

Quick Start

# Build
make build

# Run
./csvkit

# Or with custom port
./csvkit -addr :9090

# Parse CSV
curl -X POST localhost:8080/parse -d 'name,age,city
Alice,30,NYC
Bob,25,LA'

# Filter rows
curl -X POST 'localhost:8080/filter?col=age&op=gt&value=28' -d 'name,age
Alice,30
Bob,25
Charlie,35'

# Sort by column
curl -X POST 'localhost:8080/sort?col=age&order=desc' -d 'name,age
Alice,30
Bob,25'

# Convert to JSON
curl -X POST localhost:8080/to-json -d 'name,age
Alice,30'

# Pretty print
curl -X POST localhost:8080/pretty -d 'a,b
1,22
333,4'

Principles

• The agent IS the interface — No UI, no SDK. The API is the product.
• Plain text by default — CSV in, CSV out. JSON on demand via Accept: application/json or ?format=json.
• Instructive errors — Every 4xx includes a hint telling the agent what to do next.
• Self-documenting — GET /help returns a one-page operating manual.
• Single static binary — Go, CGO_ENABLED=0, zero external dependencies.
• Zero config defaults — Runs out of the box. Config: defaults < env < flags.
• MCP connector — Speaks Model Context Protocol at POST /mcp.

API Reference

Endpoint	Method	Description
/help	GET	Operating manual
/parse	POST	Parse and validate CSV
/format	POST	Re-format CSV (normalize quoting)
/pretty	POST	Format as aligned text table
/to-json	POST	Convert CSV to JSON
/from-json	POST	Convert JSON to CSV
/stats	POST	Get row/column/cell counts
/select?cols=a,b	POST	Select specific columns
/remove?cols=a,b	POST	Remove specific columns
/rename?from=a&to=x	POST	Rename a column
/add-column?name=x&value=v	POST	Add a column
/filter?col=age&op=gt&value=28	POST	Filter rows by condition
/sort?col=age&order=asc	POST	Sort rows by column
/dedup	POST	Remove duplicate rows
/transpose	POST	Swap rows and columns
/head?n=5	POST	First N rows
/tail?n=5	POST	Last N rows
/find-replace?col=name&find=old&replace=new	POST	Find and replace text
/join?left-col=id&right-col=id&type=inner	POST	Join two CSVs
/split?col=city	POST	Split by column value
/transform?col=name&op=upper	POST	Transform a column
/mcp	POST	MCP JSON-RPC 2.0 endpoint

Filter Operators

eq, ne, contains, prefix, suffix, gt, lt, ge, le

Transform Operations

upper, lower, trim, prefix, suffix, strip, replace

Join Types

inner, left, outer

Configuration

Flag	Env	Default	Description
-addr	CSVKIT_ADDR	:8080	Listen address
-no-auth	CSVKIT_NO_AUTH	false	Disable auth (dev mode)

Build

make build    # CGO_ENABLED=0 go build -trimpath
make test     # go test -race ./...
make vet      # go vet ./...

License

MIT