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join-strings

A string joiner concatenates a list of lines (or array elements) into a single string with a chosen separator between elements. It's the inverse of split-string. Daily uses: building SQL IN (...) clauses, comma-separated config strings, CSV row reconstruction, JSON-array literal generation from row data, URL query-parameter assembly, and CSV-to-prose conversion for natural-language reports. The ZTools Join Strings tool supports any separator (single char, multi-char, escape sequences like \\n, \\t), per-element quoting (single, double, backtick), prefix/suffix wrapping, and trim/dedupe/empty-skip pre-processing.

Use cases​

Build SQL IN clauses​

Paste a list of user IDs, get IN ('id1', 'id2', 'id3', ...) ready for the WHERE clause. Single-quote each element + comma separator + parens prefix/suffix.

CSV reconstruction​

Joining columns back into a CSV row after manipulation. Comma separator + double-quote each element when contents contain commas.

Comma-separated config strings​

Environment variables like ALLOWED_HOSTS=a.com,b.com,c.com. Paste hostnames as lines, join with comma, paste into .env.

JSON array literal​

Build ["item1", "item2", "item3"] from a list of names. Double-quote, comma-separate, square-bracket prefix/suffix.

Natural-language list​

Convert a list of names into "Alice, Bob, Carol, and Dave" with proper Oxford comma. The tool supports the special "human list" join mode.

How it works​

  1. Paste lines — One element per line. Up to 100,000 lines.
  2. Pick separator — Common (comma, pipe, semicolon, tab, newline) or custom (any string, including escape sequences).
  3. Optional quoting — Wrap each element in single quotes, double quotes, or backticks.
  4. Optional prefix/suffix — e.g. prefix="(", suffix=")" produces parenthesised output.
  5. Pre-process — Trim whitespace, drop empty lines, dedupe, lowercase before join.
  6. Copy result — One-click clipboard.

Examples​

Input: Lines: alice, bob, carol. Sep: ", ", quote: single, prefix: "(", suffix: ")"

Output: ('alice', 'bob', 'carol') — ready for SQL IN.

Input: Lines: 192.168.0.1, 192.168.0.2. Sep: ",", no quote

Output: 192.168.0.1,192.168.0.2 — ready for env var.

Input: Lines: red, green, blue. "Human list" mode

Output: red, green, and blue — Oxford comma included.

Frequently asked questions​

How is this different from manually typing the result?

For 5 items, manual is fine. For 50, 500, or 5000, manual is error-prone. The tool also handles edge cases (escape sequences, embedded quotes, trailing commas) you might miss.

Can the separator be a tab or newline?

Yes — use \\t for tab, \\n for newline. The tool unescapes these to actual control characters before joining.

What about elements that contain the separator?

The "quote each element" option wraps elements so embedded separators don't corrupt parsing. For CSV specifically, double-quote with double-quote escaping is the spec.

Does it handle trailing newlines correctly?

Yes — empty trailing lines are dropped by default (toggleable). Avoids the common bug of an extra empty element appearing in the output.

Why is my SQL output not safe to execute?

String concatenation is NOT safe against SQL injection. The tool helps build static IN-clauses; for user-provided data, use parameterised queries.

Can I escape embedded quotes?

Yes — toggle "escape embedded quotes". Single quotes become '' (SQL standard) or \\' (JS), depending on dialect.

Tips​

  • For SQL IN clauses, single-quote + comma + paren-wrap is the safe default; verify against your DB engine's quoting rules.
  • For CSV, use double-quote per RFC 4180 + escape embedded double quotes by doubling.
  • For JSON arrays, prefer JSON.stringify on the actual array — but for quick text-to-JSON, the joiner with double-quote + bracket wrap works.
  • For human-readable lists, "human list" mode handles the Oxford comma and "and" before the last item correctly.
  • Combine with split-strings (the inverse tool) for round-trip transforms.

Try it now​

The full join-strings runs in your browser at https://ztools.zaions.com/join-strings — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub