CalculatorsEMI, SIP, GST, percentages and more — instant, accurate, free.ConvertersUnit and number-base converters for everyday engineering.FormattersBeautify, validate and transform text and code.GeneratorsUUIDs, passwords and other things you need on demand.CryptographyHashes and encodings, computed locally in your browser.Data & TransformConvert JSON, CSV, YAML, XML & TOML — and generate code from JSON.CSV ToolsConvert, clean, filter, analyze and transform CSV files — all in your browser.Encoding & DecodingBase64, Base32/58/62, Hex, Octal and Punycode encoders & decoders.Text ToolsCase conversion, counting, sorting, dedupe, reverse and more.ValidatorsValidate JSON, YAML, XML, CSV, TOML and more — with clear error messages.Repair ToolsFix broken JSON, CSV, XML, YAML and other malformed data.Diff & CompareCompare two texts, JSON, CSV, YAML, XML and more — highlight the differences.QR & BarcodesGenerate WiFi, vCard, URL and other QR codes, plus Data Matrix & Aztec barcodes.MinifiersShrink JSON, CSS, JavaScript, XML and SVG by removing whitespace.BeautifiersPretty-print and indent CSS, HTML and JavaScript.Security & TokensJWT, HMAC, key pairs, TOTP, PKCE, secure tokens and password tools.Developer UtilitiesCron, regex, timestamp, URL, JSONPath, XPath, escaping and more.Format ConvertersMarkdown⇄HTML, env/INI/properties⇄JSON, NDJSON, SVG data-URI and more.Image ToolsResize, crop, convert, compress, recolor and extract palettes — all in your browser.Sitemap & SEOValidate, split, merge, analyse and generate XML sitemaps — paste the XML, nothing is uploaded.
Learn
Blog

Merge CSV Files

Free tool to merge two CSV files into one — columns are unioned and rows stacked — in your browser.

Learn more: CSV Files ExplainedThe CSV format, RFC 4180 quoting rules, encodings, common pitfalls, and how CSV compares to TSV, JSON and Parquet.

CSV ACSV B

Result

Shares a link with your input encoded in it — nothing is uploaded.

Runs entirely in your browser — nothing you enter is uploaded or stored.

Ask about this tool on

Merge CSV Files

Free tool to merge two CSV files into one — columns are unioned and rows stacked — in your browser.

All processing happens in your browser — your files never leave the page, which you can confirm from the Network panel or our privacy policy.

Frequently asked questions

How do I use the Merge CSV Files?

Paste your two CSV files (A and B) and the result appears below. Everything runs in your browser.

Is my data uploaded anywhere?

No. This tool runs entirely in your browser — your CSV files are never sent to a server.

Is the Merge CSV Files free?

Yes — completely free, no sign-up and no limits.

Merge CSV Files

Frequently asked questions

Related tools