Switching from WP Overnight PDF Invoices to invoice9

WP Overnight's PDF Invoices & Packing Slips is a good plugin. Three hundred thousand active installations on WordPress.org earned that honestly. If you're considering invoice9, the question isn't whether WP Overnight works — it's whether the gaps invoice9 closes are material to your store.

The honest comparison

WP Overnight ships ZUGFeRD and Factur-X. So do we. The differences sit at the edges:

• XRechnung CII — the German B2G syntax. WP Overnight ships UBL only; invoice9 ships both. If you sell to German federal or state agencies, this matters.
• PEPPOL credit notes — invoice9 ships invoice + credit note natively. WP Overnight ships invoices only.
• Marketplace integration — WP Overnight is off-marketplace. invoice9 is on the Woo Marketplace, which means integrated billing, Woo's 30-day refund policy, and one-click upgrade between site tiers via your WooCommerce.com account.
• EU data residency — WP Overnight runs everything client-side on your WordPress install. invoice9 generates server-side in Frankfurt and never persists invoice content. For German GoBD audits where the question "where is the data" comes up, our answer is unambiguous.
• Coexistence detection — invoice9 detects WP Overnight on activation and shows a one-click copy panel for your settings. You don't have to re-type your company name and logo URL. (This is literally the only direction the migration tooling exists in; WP Overnight does not detect competing plugins.)

What WP Overnight does that we don't: shipping labels, packing slips beyond the basics, and the broader document-suite mindset. If shipping labels are why you bought it, you should keep WP Overnight and add invoice9 alongside for the e-invoice formats.

The 10-minute migration

This is the one path we've actively engineered for. invoice9 reads WP Overnight's settings via WordPress's standard get_option API on the keys WP Overnight uses (wpo_wcpdf_settings_general and wpo_wcpdf_documents_settings_invoice) and offers a side-by-side copy panel.

1. Install invoice9 from the WooCommerce Marketplace.
2. Open WooCommerce → Settings → invoice9. The Coexistence card at the bottom shows: "WP Overnight detected. Copy settings into invoice9?"
3. Click "Copy all into invoice9". Your company name, address, and logo URL transfer. Read-only on WP Overnight's side — we do not modify their options.
4. Set your default e-invoice format. Auto recommended (picks per buyer locale). Save.
5. Disable WP Overnight's email attachment under WP Overnight → Documents → Invoice → "Attach to". Otherwise customers receive two PDFs per order email.
6. Generate a test invoice from a recent order. Confirm the ZUGFeRD or Factur-X output.
7. You're live. WP Overnight stays installed; its old PDFs remain in your media library; future orders go through invoice9.

What about my old invoices?

Stay where they are. WP Overnight saved them as media library attachments — invoice9 doesn't touch them, and your customers can still download via WooCommerce's own order pages. Your numbering sequence transfers cleanly because invoice9 has a "starting number" setting matching whatever WP Overnight left off at.

Why the price difference

WP Overnight's Pro tier is around $60/year for the e-invoice format add-on. invoice9 is $50/year flat — every format included on every plan, no add-on tiering. We're newer, smaller, and the volume play is part of how we compete.

Frequently asked questions

Will I lose my invoice history?

No. WP Overnight's invoices stay in your WordPress media library. invoice9 generates new invoices for new orders going forward. We do not touch existing files.

Can I run both plugins simultaneously for a transition period?

Yes. The only collision is the woocommerce_email_attachments filter — both plugins try to attach to the same email. Disable one plugin's email attachment (we recommend WP Overnight's, since invoice9 ships the structured formats) and run them side by side until you're confident.

Is the switch reversible?

Fully. invoice9 stores nothing on WP Overnight's side. Disable invoice9, re-enable WP Overnight's email attachment, and you're back where you started.

What about my numbering format?

invoice9 uses {curly} placeholder syntax (matches Germanized convention); WP Overnight uses [bracket]. The Coexistence card shows the format converter. If you're on [invoice_year]-[invoice_number] you'd port to {YYYY}-{NNNNN}.