DNS character-strings are length-prefixed by a single byte. That byte caps a single string at 255. A TXT record can contain multiple strings concatenated by the resolver — `"abc" "def"` is read as `abcdef`. The protocol leaves the join up to the application.

Does Cloudflare really auto-split?

Yes. Paste a 600-byte string into Cloudflare and it'll silently split into three character-strings under the hood. The output we show for Cloudflare is just the joined value — paste that, no quoting needed.

TXT Record Splitter (255-Byte Chunks)

A single DNS TXT character-string is capped at 255 bytes by RFC 1035. Records longer than that — RSA DKIM public keys, SPF records with many includes — have to be split into multiple character-strings concatenated by the resolver. Each DNS UI does the splitting slightly differently: BIND wants `("chunk1" "chunk2")` syntax, generic zone files want space-separated quoted strings, Cloudflare auto-splits, Route 53 wants quoted strings separated by spaces. This tool produces the form that drops into your provider's UI without further edits.

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Long TXT value

DNS UI / formatChunk size: 255 B

Input bytes

Chunks

Output bytes

Output

_record IN TXT (
  
)

DNS character-strings are length-prefixed by one byte → 255 max per string. TXT records concatenate multiple strings, which is how DKIM keys longer than that fit in DNS.

How to use

Paste your full TXT value (DKIM public key, long SPF, long DMARC). Sample buttons fill in realistic examples.
Pick the DNS UI you're publishing through. The output adjusts to that provider's quoting.
Copy and paste into the value field. The resolver re-assembles the chunks transparently for clients.

Frequently asked questions

Why 255 bytes?: DNS character-strings are length-prefixed by a single byte. That byte caps a single string at 255. A TXT record can contain multiple strings concatenated by the resolver — `"abc" "def"` is read as `abcdef`. The protocol leaves the join up to the application.
Does Cloudflare really auto-split?: Yes. Paste a 600-byte string into Cloudflare and it'll silently split into three character-strings under the hood. The output we show for Cloudflare is just the joined value — paste that, no quoting needed.

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