Free Email & Developer Tools

Check and fix the DNS records that decide whether your email reaches the inbox. No sign-up, nothing stored — just public DNS lookups.

Bahasa Indonesia

Email authentication (SPF, DKIM, DMARC)

SPF Checker

Validate SPF and count DNS lookups against the 10-lookup limit.

Open tool

DKIM Checker

Look up DKIM selectors, validate keys, and check key length.

Open tool

DMARC Checker

Check your DMARC policy, report addresses, and alignment.

Open tool

SPF Record Generator

Build a valid SPF record from the services you send with.

Open tool

DMARC Record Generator

Create a DMARC record step by step, from p=none to reject.

Open tool

Deliverability guides

Fix Gmail 550 5.7.26 "This Mail Is Unauthenticated"

SPF PermError: Too Many DNS Lookups and How to Fix It

DMARC Fails but SPF Passes? Fix Identifier Alignment

Gmail & Yahoo Bulk Sender Requirements: Setup Checklist

Where to start

If your mail is landing in spam or bouncing with errors like 550 5.7.26, work through the checks in this order:

  1. SPF — one valid record, under 10 DNS lookups.
  2. DKIM — a 2048-bit key published for the selector your provider signs with.
  3. DMARC — at least p=none with a report address, aligned with your From domain.

More developer utilities (JSON, Base64, JWT, regex, and others) are available in our full tools collection (Indonesian interface).