SPF Surveyor
See your complete SPF record as a tree — every include and redirect resolved, every DNS lookup counted against the limit of 10.
SPF (Sender Policy Framework) lets a domain publish which servers are allowed to send email on its behalf. The record looks simple — a single TXT record starting with v=spf1 — but in practice it behaves like a small program: every include: mechanism pulls in another domain's record, which can include further records in turn. The receiving server resolves this whole tree on every incoming message.
That resolution is capped hard at ten DNS lookups. Go over, and SPF returns a "permerror": most receivers then treat your record as if it did not exist, and some count it against your spam score. The limit is the single most common way SPF silently breaks — you add one more SaaS tool that "just needs an include", and lookup number eleven takes your newsletter down with it. Because the tree is invisible in your DNS panel, the breakage is invisible too.
The SPF Surveyor makes the tree visible. Enter a domain and we resolve the full chain of includes and redirects exactly like a receiver would, with loop protection, and render it as an expandable tree: each node shows the record we found, the lookups it consumes itself, and the total consumed by its subtree. A counter shows where you stand against the limit, and findings flag the classic mistakes — multiple SPF records, +all/?all endings, the deprecated ptr mechanism, dead includes pointing at domains with no record.
If you are near the limit, the fix is usually to flatten: replace includes of providers with static IP ranges by their ip4:/ip6: values, and delete includes for services you stopped using. The tree shows you exactly which branches are the expensive ones.