Help

2026-05-24

Haiku.lt is designed to help you quickly and easily create invoices and manage your billing workflow.

If you’re curious about why you should choose Haiku.lt, take a look at our philosophy. You can also review the changelog for the latest features and improvements.

Creating invoices

Create your first invoice — a step-by-step walkthrough for new users.
Invoice series and numbering — how series names work and how sequential numbering is enforced.
Invoice fields reference — every field on the new-invoice form explained.
Due dates and payment terms — payment terms, due dates, and overdue tracking.
Proforma invoices — when to use them and how they differ from regular invoices.
Credit invoices — issuing refunds without deleting the original invoice.

Managing invoices

Editing and locking invoices — making changes, marking paid, locking, and when to delete.
Batch-editing invoices — apply changes to many invoices at once via the multi-edit wizard.

Bulk creation

Create invoices from Google Calendar — generate invoices for a whole month from your calendar events.

Sending invoices

Gmail (OAuth) setup — send directly from your Gmail account, no password sharing.
SMTP setup — works with any email provider; required for non-Gmail users.
Email templates and variables — customize subject and body using Handlebars variables and line-item loops.
Brand customization — upload a logo and set brand colors used by the HTML templates.

Customization & advanced

Additional information programming — populate the additional-info field automatically with JavaScript.
InML custom PDF layouts — customize the invoice PDF using the InML template language.

Expenses

Expense tracking — record business expenses and keep receipts together with your invoices.
Google Drive integration — automatically archive invoice PDFs and expense receipts into a tidy Drive folder structure.

Integrations

Pigu integration — pull marketplace orders and turn them into invoices.