diff --git a/config.example.yaml b/config.example.yaml
index a34350a..087539f 100644
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -26,3 +26,10 @@ email:
 upload:
   max_size_mb: 15
   max_files: 10
+
+webhook:
+  rsvp_url: "" # optional; POST JSON here on every new RSVP
+  photo_url: "" # optional; POST JSON here on every photo upload
+  secret: "" # optional; HMAC-SHA256-signs the payload, sent as X-Webhook-Signature
+  headers: {} # optional; extra headers sent with every webhook request, e.g. Authorization: "Bearer xxx"
+  timeout_seconds: 5
diff --git a/server/internal/api/handlers.go b/server/internal/api/handlers.go
index a6e9f8b..6b7791a 100644
--- a/server/internal/api/handlers.go
+++ b/server/internal/api/handlers.go
@@ -17,16 +17,18 @@ import (
 	"wedding-server/internal/config"
 	"wedding-server/internal/mail"
 	"wedding-server/internal/store"
+	"wedding-server/internal/webhook"
 )
 
 type Server struct {
-	cfg    *config.Config
-	store  *store.Store
-	mailer *mail.Mailer
+	cfg     *config.Config
+	store   *store.Store
+	mailer  *mail.Mailer
+	webhook *webhook.Client
 }
 
-func New(cfg *config.Config, st *store.Store, mailer *mail.Mailer) *Server {
-	return &Server{cfg: cfg, store: st, mailer: mailer}
+func New(cfg *config.Config, st *store.Store, mailer *mail.Mailer, wh *webhook.Client) *Server {
+	return &Server{cfg: cfg, store: st, mailer: mailer, webhook: wh}
 }
 
 func (s *Server) Routes(mux *http.ServeMux) {
@@ -105,6 +107,9 @@ func (s *Server) handleRSVP(w http.ResponseWriter, r *http.Request) {
 	if err := s.mailer.SendRSVP(rsvp); err != nil {
 		log.Printf("rsvp: email failed: %v", err)
 	}
+	if err := s.webhook.SendRSVP(rsvp); err != nil {
+		log.Printf("rsvp: webhook failed: %v", err)
+	}
 
 	writeJSON(w, http.StatusCreated, map[string]bool{"ok": true})
 }
@@ -275,6 +280,9 @@ func (s *Server) handlePhotoUpload(w http.ResponseWriter, r *http.Request) {
 	if err := s.mailer.SendPhotoUpload(upload, saved); err != nil {
 		log.Printf("photos: email failed: %v", err)
 	}
+	if err := s.webhook.SendPhotoUpload(upload, saved); err != nil {
+		log.Printf("photos: webhook failed: %v", err)
+	}
 
 	writeJSON(w, http.StatusCreated, map[string]bool{"ok": true})
 }
diff --git a/server/internal/config/config.go b/server/internal/config/config.go
index 149f347..563b61a 100644
--- a/server/internal/config/config.go
+++ b/server/internal/config/config.go
@@ -15,6 +15,7 @@ type Config struct {
 	Storage StorageConfig `yaml:"storage"`
 	Email   EmailConfig   `yaml:"email"`
 	Upload  UploadConfig  `yaml:"upload"`
+	Webhook WebhookConfig `yaml:"webhook"`
 }
 
 type ServerConfig struct {
@@ -52,6 +53,17 @@ type UploadConfig struct {
 	MaxFiles  int `yaml:"max_files"`
 }
 
+// WebhookConfig is entirely optional: each URL is only called if set, so a
+// deployment can wire up RSVP notifications without touching photo uploads
+// (or either at all).
+type WebhookConfig struct {
+	RSVPURL        string            `yaml:"rsvp_url"`
+	PhotoURL       string            `yaml:"photo_url"`
+	Secret         string            `yaml:"secret"`  // signs the payload via HMAC-SHA256, sent in X-Webhook-Signature
+	Headers        map[string]string `yaml:"headers"` // extra headers sent with every webhook request, e.g. Authorization
+	TimeoutSeconds int               `yaml:"timeout_seconds"`
+}
+
 // Path resolves the config file location: $CONFIG_PATH, or ./config.yaml.
 func Path() string {
 	if p := os.Getenv("CONFIG_PATH"); p != "" {
@@ -83,6 +95,9 @@ func Load(path string) (*Config, error) {
 	if cfg.Upload.MaxFiles == 0 {
 		cfg.Upload.MaxFiles = 10
 	}
+	if cfg.Webhook.TimeoutSeconds == 0 {
+		cfg.Webhook.TimeoutSeconds = 5
+	}
 	if cfg.Wedding.Date.IsZero() {
 		return nil, fmt.Errorf("wedding.date is required in %s", path)
 	}
diff --git a/server/internal/webhook/webhook.go b/server/internal/webhook/webhook.go
new file mode 100644
index 0000000..6136f5a
--- /dev/null
+++ b/server/internal/webhook/webhook.go
@@ -0,0 +1,98 @@
+package webhook
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"wedding-server/internal/config"
+	"wedding-server/internal/store"
+)
+
+type Client struct {
+	cfg        config.WebhookConfig
+	httpClient *http.Client
+}
+
+func New(cfg config.WebhookConfig) *Client {
+	return &Client{
+		cfg:        cfg,
+		httpClient: &http.Client{Timeout: time.Duration(cfg.TimeoutSeconds) * time.Second},
+	}
+}
+
+func (c *Client) post(url, event string, data any) error {
+	if url == "" {
+		return nil
+	}
+
+	body, err := json.Marshal(map[string]any{
+		"event":  event,
+		"sentAt": time.Now().UTC(),
+		"data":   data,
+	})
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	for k, v := range c.cfg.Headers {
+		req.Header.Set(k, v)
+	}
+	if c.cfg.Secret != "" {
+		req.Header.Set("X-Webhook-Signature", sign(c.cfg.Secret, body))
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	io.Copy(io.Discard, resp.Body)
+
+	if resp.StatusCode >= 300 {
+		return fmt.Errorf("webhook %s: unexpected status %d", url, resp.StatusCode)
+	}
+	return nil
+}
+
+func sign(secret string, body []byte) string {
+	mac := hmac.New(sha256.New, []byte(secret))
+	mac.Write(body)
+	return "sha256=" + hex.EncodeToString(mac.Sum(nil))
+}
+
+func (c *Client) SendRSVP(r store.RSVP) error {
+	guests := make([]map[string]any, len(r.Guests))
+	for i, g := range r.Guests {
+		guests[i] = map[string]any{"name": g.Name, "isChild": g.IsChild}
+	}
+	return c.post(c.cfg.RSVPURL, "rsvp.created", map[string]any{
+		"guests":  guests,
+		"message": r.Message,
+	})
+}
+
+func (c *Client) SendPhotoUpload(u store.PhotoUpload, files []store.PhotoFile) error {
+	urls := make([]string, len(files))
+	for i, f := range files {
+		urls[i] = f.URL
+	}
+	return c.post(c.cfg.PhotoURL, "photos.uploaded", map[string]any{
+		"name":      u.Name,
+		"message":   u.Message,
+		"email":     u.Email,
+		"phone":     u.Phone,
+		"photoUrls": urls,
+	})
+}
diff --git a/server/main.go b/server/main.go
index e09e982..b3ce28c 100644
--- a/server/main.go
+++ b/server/main.go
@@ -14,6 +14,7 @@ import (
 	"wedding-server/internal/config"
 	"wedding-server/internal/mail"
 	"wedding-server/internal/store"
+	"wedding-server/internal/webhook"
 )
 
 //go:embed all:web/dist
@@ -37,9 +38,10 @@ func main() {
 	defer st.Close()
 
 	mailer := mail.New(cfg.Email)
+	wh := webhook.New(cfg.Webhook)
 
 	mux := http.NewServeMux()
-	api.New(cfg, st, mailer).Routes(mux)
+	api.New(cfg, st, mailer, wh).Routes(mux)
 
 	uploadsDir := filepath.Join(cfg.Storage.DataDir, "photos")
 	mux.Handle("/uploads/", http.StripPrefix("/uploads/", http.FileServer(http.Dir(uploadsDir))))