What is a DKIM selector?

A selector is an arbitrary string (like `google`, `default`, or `k1`) that allows a domain to publish multiple DKIM keys simultaneously (e.g., for Google Workspace, SendGrid, and Mailchimp).

Updated: August 2026 • Verified v1.2

DNS DKIM Key Record Generator & String Splitter

Internet & NetworkNetwork

Local Browser Execution: Your input is processed locally in your browser and is not sent to UTL servers.

Record Synthesis: [selector]._domainkey.[domain] IN TXT "v=DKIM1; k=[k]; p=[chunks]"

Was this calculation helpful?

Understanding Your Results

Constructs the full `selector._domainkey.domain` record name, formats single-line TXT values, generates RFC 4408 compliant 255-character chunked BIND zone entries, and provides terminal `dig` test commands.

Practical Guidance & Next Steps

2048-bit RSA keys are required by Google and Yahoo for bulk senders. If your DNS provider gives a 'TXT string too long' error, use the chunked multi-string format provided by this tool.

What is this?

A domain administration utility that formats DKIM public key TXT records and splits long 2048-bit keys to comply with DNS string limits.

How does it work?

1. Enter selector name (default, google, s1) and your domain. 2. Paste your base64 public key. 3. Copy the formatted single TXT record or RFC-compliant chunked BIND snippet.

Why use it?

Solves DNS syntax errors when deploying modern 2048-bit email signing keys.

Technical Scope & Calculation Limitations

Generates RFC 6376 standard DKIM TXT records.

Frequently Asked Questions

A single DNS TXT character-string is limited to 255 bytes by RFC 1035. A 2048-bit RSA public key is ~392 characters long. To publish it, the record must be split into multiple quoted strings `("chunk1" "chunk2")` which receiving mail servers automatically concatenate into one key.

Windows Desktop & Widget Options