diff --git a/cmd/app.go b/cmd/app.go
index 3c2153e9427357c498c08a02a470b1bb671908cf..5a04b12d8c59f8977fee19ec6de9db94ba8d27c4 100644
--- a/cmd/app.go
+++ b/cmd/app.go
@@ -19,6 +19,7 @@ func New() *cli.App {
 	flags := []cli.Flag{
 		&cli.StringFlag{Name: "config", Aliases: []string{"c"}, EnvVars: []string{"NTFY_CONFIG_FILE"}, Value: "/etc/ntfy/config.yml", DefaultText: "/etc/ntfy/config.yml", Usage: "config file"},
 		altsrc.NewStringFlag(&cli.StringFlag{Name: "listen-http", Aliases: []string{"l"}, EnvVars: []string{"NTFY_LISTEN_HTTP"}, Value: config.DefaultListenHTTP, Usage: "ip:port used to as listen address"}),
+		altsrc.NewStringFlag(&cli.StringFlag{Name: "cache-file", Aliases: []string{"C"}, EnvVars: []string{"NTFY_CACHE_FILE"}, Usage: "cache file used for message caching"}),
 		altsrc.NewStringFlag(&cli.StringFlag{Name: "firebase-key-file", Aliases: []string{"F"}, EnvVars: []string{"NTFY_FIREBASE_KEY_FILE"}, Usage: "Firebase credentials file; if set additionally publish to FCM topic"}),
 		altsrc.NewDurationFlag(&cli.DurationFlag{Name: "message-buffer-duration", Aliases: []string{"b"}, EnvVars: []string{"NTFY_MESSAGE_BUFFER_DURATION"}, Value: config.DefaultMessageBufferDuration, Usage: "buffer messages in memory for this time to allow `since` requests"}),
 		altsrc.NewDurationFlag(&cli.DurationFlag{Name: "keepalive-interval", Aliases: []string{"k"}, EnvVars: []string{"NTFY_KEEPALIVE_INTERVAL"}, Value: config.DefaultKeepaliveInterval, Usage: "default interval of keepalive messages"}),
@@ -44,6 +45,7 @@ func New() *cli.App {
 func execRun(c *cli.Context) error {
 	// Read all the options
 	listenHTTP := c.String("listen-http")
+	cacheFile := c.String("cache-file")
 	firebaseKeyFile := c.String("firebase-key-file")
 	messageBufferDuration := c.Duration("message-buffer-duration")
 	keepaliveInterval := c.Duration("keepalive-interval")
@@ -62,6 +64,7 @@ func execRun(c *cli.Context) error {
 
 	// Run server
 	conf := config.New(listenHTTP)
+	conf.CacheFile = cacheFile
 	conf.FirebaseKeyFile = firebaseKeyFile
 	conf.MessageBufferDuration = messageBufferDuration
 	conf.KeepaliveInterval = keepaliveInterval
diff --git a/config/config.go b/config/config.go
index cfa9e68a6287ccf6e1acb862d51f431cd0835b1e..944c1a0e1dcdda2e5b5b146e1e9b6e3df9db9125 100644
--- a/config/config.go
+++ b/config/config.go
@@ -28,6 +28,7 @@ var (
 // Config is the main config struct for the application. Use New to instantiate a default config struct.
 type Config struct {
 	ListenHTTP               string
+	CacheFile          string
 	FirebaseKeyFile          string
 	MessageBufferDuration    time.Duration
 	KeepaliveInterval        time.Duration
@@ -42,6 +43,7 @@ type Config struct {
 func New(listenHTTP string) *Config {
 	return &Config{
 		ListenHTTP:               listenHTTP,
+		CacheFile: "",
 		FirebaseKeyFile:          "",
 		MessageBufferDuration:    DefaultMessageBufferDuration,
 		KeepaliveInterval:        DefaultKeepaliveInterval,
diff --git a/go.mod b/go.mod
index a72b8fdfed1bca7d9a13e91f60f645b69a8e77b2..dc198b2bb524fc07730bcdaa0b610a126d9d38ce 100644
--- a/go.mod
+++ b/go.mod
@@ -1,16 +1,42 @@
 module heckel.io/ntfy
 
-go 1.16
+go 1.17
 
 require (
-	cloud.google.com/go/firestore v1.6.0 // indirect
+	cloud.google.com/go/firestore v1.6.1 // indirect
 	cloud.google.com/go/storage v1.18.2 // indirect
 	firebase.google.com/go v3.13.0+incompatible
 	github.com/BurntSushi/toml v0.4.1 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.1 // indirect
+	github.com/mattn/go-sqlite3 v1.14.9
 	github.com/urfave/cli/v2 v2.3.0
 	golang.org/x/oauth2 v0.0.0-20211028175245-ba495a64dcb5 // indirect
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac
 	google.golang.org/api v0.60.0
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
+
+require (
+	cloud.google.com/go v0.97.0 // indirect
+	github.com/census-instrumentation/opencensus-proto v0.3.0 // indirect
+	github.com/cespare/xxhash v1.1.0 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/cncf/udpa/go v0.0.0-20210930031921-04548b0d99d4 // indirect
+	github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1 // indirect
+	github.com/envoyproxy/go-control-plane v0.10.0 // indirect
+	github.com/envoyproxy/protoc-gen-validate v0.6.2 // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/google/go-cmp v0.5.6 // indirect
+	github.com/googleapis/gax-go/v2 v2.1.1 // indirect
+	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	go.opencensus.io v0.23.0 // indirect
+	golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d // indirect
+	golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359 // indirect
+	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/genproto v0.0.0-20211101144312-62acf1d99145 // indirect
+	google.golang.org/grpc v1.41.0 // indirect
+	google.golang.org/protobuf v1.27.1 // indirect
+)
diff --git a/go.sum b/go.sum
index 85e8f23d85d7c363b921221fd1f6dd70f5f7af34..ba19948fd321d4a5bc65d6c269dd5c799c70ac5a 100644
--- a/go.sum
+++ b/go.sum
@@ -36,6 +36,8 @@ cloud.google.com/go/datastore v1.0.0/go.mod h1:LXYbyblFSglQ5pkeyhO+Qmw7ukd3C+pD7
 cloud.google.com/go/datastore v1.1.0/go.mod h1:umbIZjpQpHh4hmRpGhH4tLFup+FVzqBi1b3c64qFpCk=
 cloud.google.com/go/firestore v1.6.0 h1:dMIWvm+3O0E3DM7kcZPH0FBQ94Xg/OMkdTNDaY9itbI=
 cloud.google.com/go/firestore v1.6.0/go.mod h1:afJwI0vaXwAG54kI7A//lP/lSPDkQORQuMkv56TxEPU=
+cloud.google.com/go/firestore v1.6.1 h1:8rBq3zRjnHx8UtBvaOWqBB1xq9jH6/wltfQLlTMh2Fw=
+cloud.google.com/go/firestore v1.6.1/go.mod h1:asNXNOzBdyVQmEU+ggO8UPodTkEVFW5Qx+rwHnAz+EY=
 cloud.google.com/go/pubsub v1.0.1/go.mod h1:R0Gpsv3s54REJCy4fxDixWD93lHJMoZTyQ2kNxGRt3I=
 cloud.google.com/go/pubsub v1.1.0/go.mod h1:EwwdRX2sKPjnvnqCa270oGRyludottCI76h+R3AArQw=
 cloud.google.com/go/pubsub v1.2.0/go.mod h1:jhfEVHT8odbXTkndysNHCcx0awwzvfOlguIAii9o8iA=
@@ -59,8 +61,13 @@ github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAE
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/census-instrumentation/opencensus-proto v0.2.1 h1:glEXhBS5PSLLv4IXzLA5yPRVX4bilULVyxxbrfOtDAk=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/census-instrumentation/opencensus-proto v0.3.0 h1:t/LhUZLVitR1Ow2YOnduCsavhwFUklBMoGVYUCqmCqk=
+github.com/census-instrumentation/opencensus-proto v0.3.0/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
+github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/cespare/xxhash/v2 v2.1.2 h1:YRXhKfTDauu4ajMg1TPgFO5jnlC2HCbmLXMcTG5cbYE=
+github.com/cespare/xxhash/v2 v2.1.2/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
@@ -69,8 +76,15 @@ github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGX
 github.com/cncf/udpa/go v0.0.0-20200629203442-efcf912fb354/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403 h1:cqQfy1jclcSy/FwLjemeg3SR1yaINm74aQyupQ0Bl8M=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
+github.com/cncf/udpa/go v0.0.0-20210930031921-04548b0d99d4 h1:hzAQntlaYRkVSFEfj9OTWlVV1H155FMD8BTKktLv0QI=
+github.com/cncf/udpa/go v0.0.0-20210930031921-04548b0d99d4/go.mod h1:6pvJx4me5XPnfI9Z40ddWsdw2W/uZgQLFXToKeRcDiI=
 github.com/cncf/xds/go v0.0.0-20210312221358-fbca930ec8ed h1:OZmjad4L3H8ncOIR8rnb5MREYqG8ixi5+WbeUsquF0c=
 github.com/cncf/xds/go v0.0.0-20210312221358-fbca930ec8ed/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cncf/xds/go v0.0.0-20211001041855-01bcc9b48dfe/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1 h1:zH8ljVhhq7yC0MIeUL/IviMtY8hx2mK8cN9wEYb8ggw=
+github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/cpuguy83/go-md2man/v2 v2.0.1 h1:r/myEWzV9lfsM1tFLgDyu0atFtJ1fXn261LKYj/3DxU=
 github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
@@ -83,8 +97,13 @@ github.com/envoyproxy/go-control-plane v0.9.9-0.20201210154907-fd9021fe5dad/go.m
 github.com/envoyproxy/go-control-plane v0.9.9-0.20210217033140-668b12f5399d/go.mod h1:cXg6YxExXjJnVBQHBLXeUAgxn2UodCpnH306RInaBQk=
 github.com/envoyproxy/go-control-plane v0.9.9-0.20210512163311-63b5d3c536b0 h1:dulLQAYQFYtG5MTplgNGHWuV2D+OBD+Z8lmDBmbLg+s=
 github.com/envoyproxy/go-control-plane v0.9.9-0.20210512163311-63b5d3c536b0/go.mod h1:hliV/p42l8fGbc6Y9bQ70uLwIvmJyVE5k4iMKlh8wCQ=
+github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.mod h1:AFq3mo9L8Lqqiid3OhADV3RfLJnjiw63cSpi+fDTRC0=
+github.com/envoyproxy/go-control-plane v0.10.0 h1:WVt4HEPbdRbRD/PKKPbPnIVavO6gk/h673jWyIJ016k=
+github.com/envoyproxy/go-control-plane v0.10.0/go.mod h1:AY7fTTXNdv/aJ2O5jwpxAPOWUZ7hQAEvzN5Pf27BkQQ=
 github.com/envoyproxy/protoc-gen-validate v0.1.0 h1:EQciDnbrYxy13PgWoY8AqoxGiPrpgBZ1R8UNe3ddc+A=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/envoyproxy/protoc-gen-validate v0.6.2 h1:JiO+kJTpmYGjEodY7O1Zk8oZcNz1+f30UtwtXoFUPzE=
+github.com/envoyproxy/protoc-gen-validate v0.6.2/go.mod h1:2t7qjJNvHPx8IjnBOzl9E9/baC+qXE/TeeyBRzgJDws=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
@@ -94,6 +113,8 @@ github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4er
 github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
+github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da h1:oI5xCqsCo564l8iNU+DwB5epxmsaqB+rhGL0m5jtYqE=
+github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.3.1/go.mod h1:sBzyDLLjw3U8JLTeZvSv8jJB+tU5PVekmnlKIyFUx0Y=
@@ -168,16 +189,24 @@ github.com/googleapis/gax-go/v2 v2.1.1/go.mod h1:hddJymUZASv3XPyGkUpKj8pPO47Rmb0
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/iancoleman/strcase v0.2.0/go.mod h1:iwCmte+B7n89clKwxIoIXy/HfoL7AsD47ZCWhYzw7ho=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
 github.com/jstemmer/go-junit-report v0.9.1/go.mod h1:Brl9GWCQeLvo8nXZwPNNblvFj/XSXhF0NWZEnDohbsk=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/lyft/protoc-gen-star v0.5.3/go.mod h1:V0xaHgaf5oCCqmcxYcWiDfTiKsZsRc87/1qhoTACD8w=
+github.com/mattn/go-sqlite3 v1.14.8/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
+github.com/mattn/go-sqlite3 v1.14.9 h1:10HX2Td0ocZpYEjhilsuo6WWtUqttj2Kb0KtD86/KYA=
+github.com/mattn/go-sqlite3 v1.14.9/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/sftp v1.10.1/go.mod h1:lYOWFsE0bwd1+KfKJaKeuokY15vzFx25BLbzYYoAxZI=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
@@ -188,10 +217,13 @@ github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQD
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72 h1:qLC7fQah7D6K1B0ujays3HV9gkFtllcxhzImRR7ArPQ=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
+github.com/spf13/afero v1.3.3/go.mod h1:5KUK8ByomD5Ti5Artl0RtHeI5pTF7MIDuXL3yY520V4=
+github.com/spf13/afero v1.6.0/go.mod h1:Ai8FlHk4v/PARR026UzYexafAt9roJ7LcLMAmO6Z93I=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/urfave/cli/v2 v2.3.0 h1:qph92Y649prgesehzOrQjdWyxFOp/QVM+6imKHad91M=
 github.com/urfave/cli/v2 v2.3.0/go.mod h1:LJmUH05zAU44vOAcrfzZQKsZbVcdbOG8rtL3/XcUArI=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
@@ -211,6 +243,7 @@ go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqe
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20190820162420-60c769a6c586/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -248,6 +281,7 @@ golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.1/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/mod v0.5.0/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -284,6 +318,8 @@ golang.org/x/net v0.0.0-20210316092652-d523dce5a7f4/go.mod h1:RBQZq4jEuRlivfhVLd
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20210503060351-7fd8e65b6420 h1:a8jGStKg0XqKDlKqjLrXn0ioF5MH36pT7Z0BRTqLhbk=
 golang.org/x/net v0.0.0-20210503060351-7fd8e65b6420/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d h1:LO7XpTYMwTqxjLcGWPijK3vRXg1aWdlNOVOHRq45d7c=
+golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -356,9 +392,11 @@ golang.org/x/sys v0.0.0-20210603125802-9665404d3644/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210616094352-59db8d763f22/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210816183151-1e6c022a8912/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210823070655-63515b42dcdf/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210908233432-aa78b53d3365/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210917161153-d61c044b1678/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359 h1:2B5p2L5IfGiD7+b9BOoRMC6DgObAVZV+Fsp050NqXik=
 golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
@@ -371,6 +409,8 @@ golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.5/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -462,6 +502,7 @@ google.golang.org/api v0.55.0/go.mod h1:38yMfeP1kfjsl8isn0tliTjIb1rJXcQi4UXlbqiv
 google.golang.org/api v0.56.0/go.mod h1:38yMfeP1kfjsl8isn0tliTjIb1rJXcQi4UXlbqivdVE=
 google.golang.org/api v0.57.0/go.mod h1:dVPlbZyBo2/OjBpmvNdpn2GRm6rPy75jyU7bmhdrMgI=
 google.golang.org/api v0.58.0/go.mod h1:cAbP2FsxoGVNwtgNAmmn3y5G1TWAiVYRmg4yku3lv+E=
+google.golang.org/api v0.59.0/go.mod h1:sT2boj7M9YJxZzgeZqXogmhfmRWDtPzT31xkieUbuZU=
 google.golang.org/api v0.60.0 h1:eq/zs5WPH4J9undYM9IP1O7dSr7Yh8Y0GtSCpzGzIUk=
 google.golang.org/api v0.60.0/go.mod h1:d7rl65NZAkEQ90JFzqBjcRq1TVeG5ZoGV3sSpEnnVb4=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
@@ -529,9 +570,13 @@ google.golang.org/genproto v0.0.0-20210903162649-d08c68adba83/go.mod h1:eFjDcFEc
 google.golang.org/genproto v0.0.0-20210909211513-a8c4777a87af/go.mod h1:eFjDcFEctNawg4eG61bRv87N7iHBWyVhJu7u1kqDUXY=
 google.golang.org/genproto v0.0.0-20210917145530-b395a37504d4/go.mod h1:eFjDcFEctNawg4eG61bRv87N7iHBWyVhJu7u1kqDUXY=
 google.golang.org/genproto v0.0.0-20210924002016-3dee208752a0/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211008145708-270636b82663/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211016002631-37fc39342514/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211021150943-2b146023228c h1:FqrtZMB5Wr+/RecOM3uPJNPfWR8Upb5hAPnt7PU6i4k=
 google.golang.org/genproto v0.0.0-20211021150943-2b146023228c/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211028162531-8db9c33dc351/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211101144312-62acf1d99145 h1:vum3nDKdleYb+aePXKFEDT2+ghuH00EgYp9B7Q7EZZE=
+google.golang.org/genproto v0.0.0-20211101144312-62acf1d99145/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
 google.golang.org/grpc v1.21.1/go.mod h1:oYelfM1adQP15Ek0mdvEgi9Df8B9CZIaU1084ijfRaM=
@@ -558,6 +603,8 @@ google.golang.org/grpc v1.39.0/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnD
 google.golang.org/grpc v1.39.1/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnDzfrE=
 google.golang.org/grpc v1.40.0 h1:AGJ0Ih4mHjSeibYkFGh1dD9KJ/eOtZ93I6hoHhukQ5Q=
 google.golang.org/grpc v1.40.0/go.mod h1:ogyxbiOoUXAkP+4+xa6PZSE9DZgIHtSpzjDTB9KAK34=
+google.golang.org/grpc v1.41.0 h1:f+PlOh7QV4iIJkPrx5NQ7qaNGFQ3OTse67yaDHfju4E=
+google.golang.org/grpc v1.41.0/go.mod h1:U3l9uK9J0sini8mHphKoXyaqDA/8VyGnDee1zzIUK6k=
 google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.1.0/go.mod h1:6Kw0yEErY5E/yWrBtf03jp27GLLJujG4z/JK95pnjjw=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
diff --git a/server/cache.go b/server/cache.go
new file mode 100644
index 0000000000000000000000000000000000000000..be4f704e0b6c0d6b33c77e103c0dbc79f5347c4a
--- /dev/null
+++ b/server/cache.go
@@ -0,0 +1,61 @@
+package server
+
+import (
+	"database/sql"
+	"time"
+	_ "github.com/mattn/go-sqlite3" // SQLite driver
+)
+
+const (
+	createTableQuery = `CREATE TABLE IF NOT EXISTS messages (
+		id VARCHAR(20) PRIMARY KEY,
+		time INT NOT NULL,
+		topic VARCHAR(64) NOT NULL,
+		message VARCHAR(1024) NOT NULL
+	)`
+	insertQuery         = `INSERT INTO messages (id, time, topic, message) VALUES (?, ?, ?, ?)`
+	pruneOlderThanQuery = `DELETE FROM messages WHERE time < ?`
+)
+
+type cache struct {
+	db *sql.DB
+	insert *sql.Stmt
+	prune *sql.Stmt
+}
+
+func newCache(filename string) (*cache, error) {
+	db, err := sql.Open("sqlite3", filename)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := db.Exec(createTableQuery); err != nil {
+		return nil, err
+	}
+	insert, err := db.Prepare(insertQuery)
+	if err != nil {
+		return nil, err
+	}
+	prune, err := db.Prepare(pruneOlderThanQuery)
+	if err != nil {
+		return nil, err
+	}
+	return &cache{
+		db:     db,
+		insert: insert,
+		prune:  prune,
+	}, nil
+}
+
+func (c *cache) Load() (map[string]*topic, error) {
+
+}
+
+func (c *cache) Add(m *message) error {
+	_, err := c.insert.Exec(m.ID, m.Time, m.Topic, m.Message)
+	return err
+}
+
+func (c *cache) Prune(olderThan time.Duration) error {
+	_, err := c.prune.Exec(time.Now().Add(-1 * olderThan).Unix())
+	return err
+}
diff --git a/server/index.html b/server/index.html
index 551670ca5d4d72fc5041ddb4e6473c563c31e480..94f65f17406807e0f033cc1b5c8a6ea53be4c13a 100644
--- a/server/index.html
+++ b/server/index.html
@@ -191,7 +191,7 @@
 
     <p>
         The web server does not log or otherwise store request paths, remote IP addresses or even topics or messages,
-        aside from a short on-disk cache (up to a day) to support the <tt>since=</tt> feature and service restarts.
+        aside from a short on-disk cache (up to a day) to support service restarts.
     </p>
 
     <center id="ironicCenterTagDontFreakOut"><i>Made with ❤️ by <a href="https://heckel.io">Philipp C. Heckel</a></i></center>
diff --git a/server/server.go b/server/server.go
index dcee296e601382c5f0259da8a6641272a6c2f470..7da406713de48fe4e1e9dc4cf211a29b08d65bb2 100644
--- a/server/server.go
+++ b/server/server.go
@@ -23,7 +23,6 @@ import (
 )
 
 // TODO add "max messages in a topic" limit
-// TODO implement persistence
 // TODO implement "since=<ID>"
 
 // Server is the main server
@@ -33,6 +32,7 @@ type Server struct {
 	visitors map[string]*visitor
 	firebase subscriber
 	messages int64
+	cache *cache
 	mu       sync.Mutex
 }
 
@@ -78,14 +78,32 @@ func New(conf *config.Config) (*Server, error) {
 			return nil, err
 		}
 	}
+	cache, err := maybeCreateCache(conf)
+	if err != nil {
+		return nil, err
+	}
+	topics := make(map[string]*topic)
+	if cache != nil {
+		if topics, err = cache.Load(); err != nil {
+			return nil, err
+		}
+	}
 	return &Server{
 		config:   conf,
+		cache: cache,
 		firebase: firebaseSubscriber,
-		topics:   make(map[string]*topic),
+		topics:   topics,
 		visitors: make(map[string]*visitor),
 	}, nil
 }
 
+func maybeCreateCache(conf *config.Config) (*cache, error) {
+	if conf.CacheFile == "" {
+		return nil, nil
+	}
+	return newCache(conf.CacheFile)
+}
+
 func createFirebaseSubscriber(conf *config.Config) (subscriber, error) {
 	fb, err := firebase.NewApp(context.Background(), nil, option.WithCredentialsFile(conf.FirebaseKeyFile))
 	if err != nil {
@@ -180,9 +198,13 @@ func (s *Server) handlePublish(w http.ResponseWriter, r *http.Request, v *visito
 	if err != nil {
 		return err
 	}
-	if err := t.Publish(newDefaultMessage(t.id, string(b))); err != nil {
+	m := newDefaultMessage(t.id, string(b))
+	if err := t.Publish(m); err != nil {
 		return err
 	}
+	if s.cache != nil {
+		s.cache.Add(m)
+	}
 	w.Header().Set("Access-Control-Allow-Origin", "*") // CORS, allow cross-origin requests
 	s.mu.Lock()
 	s.messages++
@@ -337,6 +359,13 @@ func (s *Server) updateStatsAndExpire() {
 		}
 	}
 
+	// Prune cache
+	if s.cache != nil {
+		if err := s.cache.Prune(s.config.MessageBufferDuration); err != nil {
+			log.Printf("error pruning cache: %s", err.Error())
+		}
+	}
+
 	// Prune old messages, remove subscriptions without subscribers
 	for _, t := range s.topics {
 		t.Prune(s.config.MessageBufferDuration)
diff --git a/server/topic.go b/server/topic.go
index 037f4857a8cb30287d566283c407f9f045ff5633..3ad98fc5ac51955c42b39774de0fe229c7bdba92 100644
--- a/server/topic.go
+++ b/server/topic.go
@@ -29,6 +29,7 @@ func newTopic(id string) *topic {
 	return &topic{
 		id:          id,
 		subscribers: make(map[int]subscriber),
+		messages: make([]*message, 0),
 		last:        time.Now(),
 		ctx:         ctx,
 		cancel:      cancel,