Open locally
Choose, drop or paste data. Detection shows confidence and never hides ambiguity.
SPARKPOND / JOIN CSV
Join two CSV tables locally
Preview left, inner, right or full joins and unmatched rows without uploading data.
LOCAL WORKSPACE
Add your data files
CSV, TSV, JSON, NDJSON and XLSX. or drop them here.
A transparent workflow
From file to verified result in three steps
Preview changes
Choose matching keys and estimate the resulting rows.
Export after validation
The engine checks rows, columns, headers and formula risks before download.
HONEST LIMITS
What this tool does—and does not do
- iYour browser determines practical file size limits.
- iAmbiguous repairs always require confirmation.
- iXLSX formulas are never executed and encrypted workbooks are refused.
- iThis is not an antivirus or a business-data certification.
FAQ
Common questions
Is my file uploaded?
No. Content, name, columns, values and exports stay in the browser.
What file size is supported?
Capacity depends on browser and memory. The app selects interactive, large-file or streaming mode before reaching a limit.
Are long identifiers and leading zeros preserved?
Yes. Fields remain text until an explicit type conversion is added.