> For the complete documentation index, see [llms.txt](https://invoice4u.gitbook.io/invoice4u-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://invoice4u.gitbook.io/invoice4u-docs/documents/overview.md).

# Document Endpoints Overview

Documents are the core of the Invoice4U API: invoices, receipts, invoice-receipts, credit invoices, quotes, orders and more. Once created, a document is signed, numbered, and legally final — it cannot be edited, only credited or cancelled by a follow-up document.

### Endpoints in this section

| Endpoint                                                                                                                                                                               | Page                                                                                              |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------- |
| `CreateDocument`                                                                                                                                                                       | [Create a Document](/invoice4u-docs/documents/create-document.md)                                 |
| `CreateDocumentWithIdentifierValidation`                                                                                                                                               | [Create with Identifier Validation](/invoice4u-docs/documents/create-document-with-validation.md) |
| `GetDocument`, `GetDocumentByNumber`, `GetDocumentByApiIdentifier`, `IsDocumentExistsByApiIdentifier`                                                                                  | [Get a Single Document](/invoice4u-docs/documents/get-document.md)                                |
| `GetDocuments`                                                                                                                                                                         | [Search Documents](/invoice4u-docs/documents/search-documents.md)                                 |
| `CreateOrUpdateDraftDocument`, `GetDraftDocument`, `GetDraftDocuments`, `DeleteDraftDocument`, `DeleteDraftDocuments`, `CheckIfDraftExistsByDocumentType`, `GetPreviewDocumentByToken` | [Draft Documents](/invoice4u-docs/documents/draft-documents.md)                                   |
| `FetchAllocationNumber`, `UpdateAllocationNumber`                                                                                                                                      | [Allocation Numbers (Israel Tax)](/invoice4u-docs/documents/allocation-numbers.md)                |

### Reference pages

* [Document Types](/invoice4u-docs/documents/document-types.md) — the `DocumentType` enum and what each type requires
* [The Document Object](/invoice4u-docs/documents/document-object.md) — full field reference for `Document`, `DocumentItem`, `Payment`, `Discount` and related objects

### Typical creation flow

1. Authenticate → token.
2. Resolve the customer: existing `ClientID`, or supply a `GeneralCustomer` (allowed only for some types).
3. Build the `Document`: type, items and/or payments, emails to send to.
4. `POST /CreateDocument`.
5. Check `Errors`; on success, use the returned `DocumentNumber`, `ID` and the `PrintOriginalPDFLink` / `PrintCertifiedCopyPDFLink` fields.

```mermaid
flowchart TD
    classDef step fill:#E7D9FC,stroke:#9B6DD6,color:#333
    classDef dec fill:#D2F0D2,stroke:#4CAF50,color:#333
    classDef err fill:#FFD9A0,stroke:#E8A33D,color:#333
    classDef cb fill:#BBDEFB,stroke:#42A5F5,color:#333

    A[CreateDocument]:::step --> B{Token valid?}:::dec
    B -- ✗ --> E1[UnauthorizedUser 80]:::err
    B -- ✓ --> C[Defaults applied: IssueDate · TaxPercentage ·<br/>Currency · ConversionRate · BranchID · Language]:::step
    C --> D{Validations}:::dec
    D -- "type / customer" --> E2[DocumentTypeNotInRange 33<br/>ClientDoesntExists 7 · ClientIDDoesntExists 37]:::err
    D -- items --> E3[DocumentItemsNotSpecified 34 · DocumentItemMissingName 39<br/>DocumentItemQuantityCannotBeZero 40 · DocumentItemPriceCannotBeZero 41]:::err
    D -- payments --> E4[PaymentsNotSpecified 45 · PaymentDateMissing 46<br/>PaymentAmountCannotBeZero 47 · PaymentTypeOutOfRange 51]:::err
    D -- "date / quota" --> E5[InvalidDateRange 3<br/>NotEnoughDocuments 65 · NotEnoughCredits 18]:::err
    D -- ✓ --> F{Duplicate within<br/>ApiDuplicityTimeValidation?}:::dec
    F -- ✓ --> E6[DocumentAlreadyCreated 134]:::err
    F -- ✗ --> G[Created: legal DocumentNumber ·<br/>totals computed server-side]:::step
    G --> H[Ciphers → PrintOriginalPDFLink /<br/>PrintCertifiedCopyPDFLink]:::step
    H --> I{Delivery}:::dec
    I -- AssociatedEmails --> J[Email — or 2Sign<br/>signing task]:::cb
    I -- SmsMessages --> K[SMS with link]:::cb
    I --> L[Document in response]:::cb
```

### Duplicate protection

Two mechanisms prevent double-billing when your system retries:

| Mechanism                    | How it works                                                                                                                                                                                                                                                                                                                                                   |
| ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ApiIdentifier`              | Your unique ID for the document. If you don't send one, the API generates `I4U-APIGEN-<guid>`. With [CreateDocumentWithIdentifierValidation](/invoice4u-docs/documents/create-document-with-validation.md) the call is rejected with `DocumentAlreadyCreated` (134) if a document with the same identifier already exists — the existing document is returned. |
| `ApiDuplicityTimeValidation` | Time window in **seconds** (default `60`). If an identical document was created within the window, `CreateDocument` fails with `DocumentAlreadyCreated` (134). Set to a larger value for slow retry queues.                                                                                                                                                    |

### Sending by email & SMS

* `AssociatedEmails` on the document triggers email delivery of the document on creation.
* `SmsMessages` triggers SMS delivery (requires SMS credit on the account).
* `EmailCustomComment` customizes the email body comment.