diff --git a/personal/arsenicum/invoicer/src/main/java/pl/hackerspace/service/InvoiceService.java b/personal/arsenicum/invoicer/src/main/java/pl/hackerspace/service/InvoiceService.java
new file mode 100644
index 0000000..2cdb88e
--- /dev/null
+++ b/personal/arsenicum/invoicer/src/main/java/pl/hackerspace/service/InvoiceService.java
@@ -0,0 +1,143 @@
+package pl.hackerspace.service;
+
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.core.io.InputStreamResource;
+import org.springframework.core.io.Resource;
+import org.springframework.http.ContentDisposition;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.StreamUtils;
+import pl.hackerspace.domain.Client;
+import pl.hackerspace.domain.Invoice;
+import pl.hackerspace.dto.CustomInvoiceDataDto;
+import pl.hackerspace.dto.InvoiceGenerationDto;
+import pl.hackerspace.repository.ClientRepository;
+import pl.hackerspace.repository.InvoiceRepository;
+
+import java.io.BufferedInputStream;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+import static pl.hackerspace.service.TemplateService.withTemplate;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class InvoiceService {
+
+    private final ClientRepository clientRepository;
+
+    private final InvoiceRepository invoiceRepository;
+
+    @Transactional
+    public ResponseEntity<Resource> generateNewInvoice(InvoiceGenerationDto generationRequest) throws IOException {
+        Client client = clientRepository.findById(generationRequest.getNip()).orElseThrow(() -> new RuntimeException("Not found"));
+        return withTemplate(template -> {
+            byte[] invoice;
+            if (!client.isSubscriber() || generationRequest.getCustomInvoiceData() != null) {
+                invoice = createPdfInvoice(client, template, null, generationRequest.getCustomInvoiceData());
+            } else {
+                invoice = getOrCreateSubscriptionPdfInvoice(template, client, generationRequest.getMonthOfInvoice());
+            }
+            return ResponseEntity.ok()
+                    .headers(getHttpHeaders(client.getName() + " " + generationRequest.getMonthOfInvoice()))
+                    .contentLength(-1)
+                    .contentType(MediaType.APPLICATION_PDF)
+                    .body(new ByteArrayResource(invoice));
+        });
+    }
+
+
+    @Transactional
+    public void generateInvoicesForAllSubscribers(HttpServletResponse response, String monthOfInvoice) throws IOException {
+        setHeaders(response, "application/zip", LocalDate.now().format(DateTimeFormatter.ISO_LOCAL_DATE) + ".zip");
+        List<Client> subscribers = clientRepository.findBySubscriberTrue();
+        withTemplate(template -> {
+            try (ZipOutputStream zipOutputStream = new ZipOutputStream(response.getOutputStream())) {
+                for (Client client : subscribers) {
+                    try (InputStream inputStream = new ByteArrayInputStream(
+                            getOrCreateSubscriptionPdfInvoice(template, client, monthOfInvoice))) {
+                        zipOutputStream.putNextEntry(new ZipEntry(getPdfFilename(client.getName() + " "
+                                + monthOfInvoice)));
+                        StreamUtils.copy(inputStream, zipOutputStream);
+                        zipOutputStream.flush();
+                    }
+                }
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            return null;
+        });
+    }
+
+    private byte[] getOrCreateSubscriptionPdfInvoice(String template, Client client, final String monthOfInvoice) {
+        byte[] invoice = client.getInvoiceForSubscriptionMonth(monthOfInvoice);
+        if (invoice == null) {
+            invoice = createPdfInvoice(client, template, monthOfInvoice, null);
+        }
+        return invoice;
+    }
+
+    private static void setHeaders(HttpServletResponse response, String contentType, String filename) {
+        response.setContentType(contentType);
+        response.setHeader(HttpHeaders.CONTENT_DISPOSITION, ContentDisposition.attachment()
+                .filename(filename, StandardCharsets.UTF_8)
+                .build()
+                .toString());
+    }
+
+    private byte[] createPdfInvoice(Client client, String template, String monthOfSubscription,
+                                    CustomInvoiceDataDto customInvoiceData) {
+        LocalDateTime creationDate = LocalDateTime.now();
+        Invoice newInvoice = createNewInvoice(client, creationDate, monthOfSubscription);
+        byte[] bytes = TemplateService.convertHtmlToPdf(template, client, creationDate,
+                newInvoice.getInvoiceTitle(), monthOfSubscription, customInvoiceData);
+        newInvoice.setPdfContent(bytes);
+        save(newInvoice);
+        return bytes;
+    }
+
+    private static HttpHeaders getHttpHeaders(final String filename) {
+        HttpHeaders headers = new HttpHeaders();
+        headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, HttpHeaders.CONTENT_DISPOSITION);
+        headers.add(HttpHeaders.CONTENT_TYPE, "application/octet-stream");
+        headers.add(HttpHeaders.CONTENT_DISPOSITION, "inline; filename=" + getPdfFilename(filename));
+        return headers;
+    }
+
+    private static String getPdfFilename(String filename) {
+        return filename + ".pdf";
+    }
+
+    public Invoice createNewInvoice(Client client, final LocalDateTime creationDate, String monthOfSubscription) {
+        long nextInvoiceId = invoiceRepository.getMaxId() + 1;
+        return Invoice.builder().id(nextInvoiceId)
+                .invoiceTitle("FV" + nextInvoiceId)
+                .creationDate(creationDate)
+                .monthOfSubscription(monthOfSubscription)
+                .client(client)
+                .build();
+    }
+
+    public void save(Invoice newInvoice) {
+        invoiceRepository.save(newInvoice);
+    }
+
+    public List<Invoice> findAll() {
+        return invoiceRepository.findAll();
+    }
+}