// spam filtering api for forms
Junk mail stops here. Real mail gets through.
One API call classifies every form submission — spam, solicitor, lead, or support — before you spend a single Resend send. No IP tracking. No tokens burned on obvious junk.
Free to start · no credit card · unlimited websites
const res = await fetch(
"https://sendworth.dev/api/v1/check",
{
method: "POST",
headers: {
"Authorization": `Bearer ${SENDWORTH_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
email: submission.email,
name: submission.name,
message: submission.message,
}),
}
)
const { category, isSpam } = await res.json()
// "lead" | "spam" | "solicitor" | "support-request"
if (!isSpam) {
await resend.emails.send({ /* real mail only */ })
}- No IP tracking, ever
- Three layers, cheapest first
- One key, every site
- Sub-100ms fast checks
- Unlimited websites
- Free: 100 checks/mo
× how it works
Most form mail is junk. You pay to send it anyway.
Every submission runs through fast, free checks before it ever touches the AI. Cheapest layer first — an accurate category without burning tokens on obvious junk.
Layer 01 — Free
Domain reputation
The sender domain is matched against a disposable-email blocklist that refreshes daily. Throwaway domains get flagged instantly — no LLM tokens spent.
Layer 02 — Free
Sender reputation
The address is checked against a global abuse database of known spammers and forum abusers. Repeat offenders never reach the expensive step.
Layer 03 — AI
Content check
Anything that survives goes to an LLM tuned to your brand. It reads the actual message and returns a category, a confidence score, and a reason.
// deliberate omission
We never check IP addresses
IP reputation is noisy, punishes people on shared networks and VPNs, and creates privacy headaches. We skip it entirely and rely on signals that actually correlate with spam.
× features
Built for the form handler, not the marketing site.
Drop it into any handler and let it do the filtering. Everything is an API first.
001
Smart categorization
Every submission comes back as spam, solicitor, lead, or support request — route, store, or ignore it programmatically.
002
Custom categories
On Pro, add your own categories and enable or disable any of them. Disabled categories are dropped from the model entirely.
003
Brand-tailored AI
Scrape your site or upload docs so the classifier understands your product and tone. A "lead" for you is not a "lead" for everyone.
004
Learns from corrections
Relabel a submission in the dashboard and the model uses it as a correction example the next time it classifies similar mail.
005
Follow-up replies
Reply to real leads and support requests without leaving the dashboard. Sending and templates are free; AI drafts a reply in your brand voice and sends through your Resend account.
006
Own your data
Export any submission — or your entire history — as CSV or JSON, on any plan. Delete individual records or clear a whole category whenever you want.
007
Works with any integration
It is a plain HTTP endpoint — call it from Discord bots, Zapier workflows, n8n pipelines, Slack apps, Cloudflare Workers, or any serverless function. If it can make a fetch call, it works.
008
One key, every site
Use a single API key across as many forms and websites as you want. Rotate or revoke keys any time.
009
Metrics that matter
Checks used, category breakdowns, and a full log of captured submissions, right from your dashboard.
× see it in action
Request in. Verdict out.
Send the raw submission. Get back a structured verdict you can branch on.
POST /api/v1/check
Authorization: Bearer ig_live_xxx
{
"email": "growth@bestseoagency.biz",
"name": "Kyle from BestSEO",
"message": "We can get you to page 1
of Google. Reply for quote!"
}{
"category": "solicitor",
"isSpam": true,
"confidence": 0.94,
"reason": "Unsolicited SEO pitch
from a cold sender.",
"signals": {
"disposableDomain": false,
"senderReputation": "suspicious"
}
}× pricing
Pricing that scales with your forms.
Start free with 100 checks a month. Upgrade when your forms get busy.
// last step
Give your Resend quota a break.
Wire up Sendworth in a few minutes and stop paying to email spammers. Free to start, no credit card.