Production-grade input validation and fact monitoring APIs for developers. One API key, one monthly allowance, and evidence that never pretends to be certainty.
Choose a sample, run the check, and see exactly what comes back. The homepage uses demo data and never spends credits.
Every result states what was checked, when it was checked, and what it does not prove.
Catch broken, disposable, role-based, and free-provider addresses before they pollute your workflow.
02 · /v1/vat/checkValidate an EU VAT number against VIES and keep the timestamp and request evidence.
03 · /v1/iban/checkNormalize an IBAN and verify its country structure, length, and checksum locally.
04 · /v1/cpsc/recall-matchMatch product identity against U.S. recalls and Product Safety Warnings, then keep catalogs under watch.
05 · /v1/knowledge/watchesWatch named facts on public static web pages and receive a webhook only when meaning changes.
FREE HELPERDNS, MX, TLS and RDAP signals for registrable domains. Free up to 100 checks per workspace each day.
LookTwice records quiet checks in the background and sends a webhook only when a named fact meaningfully changes.
Meaningful change found
Use the same authentication, billing, event history, and webhook signature across every product.
Scopes, rotation, spend caps, and per-workspace rate limits are built in.
Charged requests are idempotent. Retries never silently spend twice.
Source, timestamp, content hash, and honest status travel with the result.
Everything you need to know about validation boundaries, uptime, and integration.
When a national tax registry (such as Germany DE or Italy IT) is temporarily unavailable for maintenance, LookTwice returns HTTP 503 and charges 0 credits. We never falsely flag valid customer VAT numbers as invalid during upstream downtime.
LookTwice performs ISO 7064 MOD-97-10 mathematical checksum verification alongside country-specific length and structure formatting pinned to SWIFT IBAN Registry Release 102 across 102 countries.
We evaluate MX cluster records, dynamic burner domain pools, role accounts, and free email providers in under 30 milliseconds. We never probe recipient mailboxes or risk deliverability penalties.
Yes. LookTwice provides official Model Context Protocol (MCP) server packages for Cursor, Windsurf, and Claude Code, alongside official community nodes for n8n visual automation.
Every account gets 100 free API units each month, shared across all APIs. Paid plans add volume and higher rate limits.