diff --git a/cmd/mediaapi-integration-tests/main.go b/cmd/mediaapi-integration-tests/main.go
index 4c584979c..c867a7126 100644
--- a/cmd/mediaapi-integration-tests/main.go
+++ b/cmd/mediaapi-integration-tests/main.go
@@ -24,9 +24,9 @@ import (
 	"path/filepath"
 	"time"
 
+	"github.com/hjson/hjson-go"
 	"github.com/matrix-org/dendrite/internal/test"
 	"github.com/matrix-org/gomatrixserverlib"
-	"gopkg.in/yaml.v2"
 )
 
 var (
@@ -45,22 +45,32 @@ var (
 	kafkaURI = test.Defaulting(os.Getenv("KAFKA_URIS"), "localhost:9092")
 )
 
-var thumbnailSizes = (`
-- width: 32
-  height: 32
-  method: crop
-- width: 96
-  height: 96
-  method: crop
-- width: 320
-  height: 240
-  method: scale
-- width: 640
-  height: 480
-  method: scale
-- width: 800
-  height: 600
-  method: scale
+var thumbnailSizes = (`[
+{
+  Width: 32
+  Height: 32
+  Method: crop
+}
+{
+  Width: 96
+  Height: 96
+  Method: crop
+}
+{
+  Width: 320
+  Height: 240
+  Method: scale
+}
+{
+  Width: 640
+  Height: 480
+  Method: scale
+}
+{
+  Width: 800
+  Height: 600
+  Method: scale
+}
 `)
 
 const serverType = "media-api"
@@ -90,7 +100,7 @@ func startMediaAPI(suffix string, dynamicThumbnails bool) (*exec.Cmd, chan error
 	}
 	cfg.Global.ServerName = gomatrixserverlib.ServerName(proxyAddr)
 	cfg.MediaAPI.DynamicThumbnails = dynamicThumbnails
-	if err = yaml.Unmarshal([]byte(thumbnailSizes), &cfg.MediaAPI.ThumbnailSizes); err != nil {
+	if err = hjson.Unmarshal([]byte(thumbnailSizes), &cfg.MediaAPI.ThumbnailSizes); err != nil {
 		panic(err)
 	}
 
diff --git a/internal/config/config.go b/internal/config/config.go
index 38b84e8b5..10f3af7eb 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -25,11 +25,11 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/hjson/hjson-go"
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/crypto/ed25519"
-	yaml "gopkg.in/yaml.v2"
 
 	jaegerconfig "github.com/uber/jaeger-client-go/config"
 	jaegermetrics "github.com/uber/jaeger-lib/metrics"
@@ -191,7 +191,7 @@ func loadConfig(
 	c.Defaults()
 
 	var err error
-	if err = yaml.Unmarshal(configData, &c); err != nil {
+	if err = hjson.Unmarshal(configData, &c); err != nil {
 		return nil, err
 	}
 
diff --git a/internal/config/config_appservice.go b/internal/config/config_appservice.go
index 68845fb57..183b4b6ed 100644
--- a/internal/config/config_appservice.go
+++ b/internal/config/config_appservice.go
@@ -43,9 +43,9 @@ func (c *AppServiceAPI) Defaults() {
 }
 
 func (c *AppServiceAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "app_service_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "app_service_api.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "app_service_api.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "AppServiceAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "AppServiceAPI.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "AppServiceAPI.Database.ConnectionString", string(c.Database.ConnectionString))
 }
 
 // ApplicationServiceNamespace is the namespace that a specific application
diff --git a/internal/config/config_clientapi.go b/internal/config/config_clientapi.go
index aadf06aea..9ca4e3fda 100644
--- a/internal/config/config_clientapi.go
+++ b/internal/config/config_clientapi.go
@@ -9,8 +9,8 @@ type ClientAPI struct {
 	Matrix  *Global  `json:"-"`
 	Derived *Derived `json:"-"` // TODO: Nuke Derived from orbit
 
-	Listen                   Address `json:"listen" comment:"The listen address for this component."`
-	Bind                     Address `json:"bind" comment:"The bind address for this component."`
+	Listen                   Address `json:"Listen" comment:"The listen address for this component."`
+	Bind                     Address `json:"Bind" comment:"The bind address for this component."`
 	RegistrationDisabled     bool    `json:"RegistrationDisabled" comment:"Prevent new users from registering, except when using the shared secret from the\nRegistrationSharedSecret option below."`
 	RegistrationSharedSecret string  `json:"RegistrationSharedSecret" comment:"If set, allows registration by anyone who knows the shared secret, even if\nregistration is otherwise disabled."`
 	RecaptchaEnabled         bool    `json:"RecaptchaEnabled" comment:"Whether to require ReCAPTCHA for registration."`
@@ -34,12 +34,12 @@ func (c *ClientAPI) Defaults() {
 }
 
 func (c *ClientAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "client_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "client_api.bind", string(c.Bind))
+	checkNotEmpty(configErrs, "ClientAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "ClientAPI.Bind", string(c.Bind))
 	if c.RecaptchaEnabled {
-		checkNotEmpty(configErrs, "client_api.recaptcha_public_key", string(c.RecaptchaPublicKey))
-		checkNotEmpty(configErrs, "client_api.recaptcha_private_key", string(c.RecaptchaPrivateKey))
-		checkNotEmpty(configErrs, "client_api.recaptcha_siteverify_api", string(c.RecaptchaSiteVerifyAPI))
+		checkNotEmpty(configErrs, "ClientAPI.RecaptchaPublicKey", string(c.RecaptchaPublicKey))
+		checkNotEmpty(configErrs, "ClientAPI.RecaptchaPrivateKey", string(c.RecaptchaPrivateKey))
+		checkNotEmpty(configErrs, "ClientAPI.RecaptchaSiteVerifyAPI", string(c.RecaptchaSiteVerifyAPI))
 	}
 	c.TURN.Verify(configErrs)
 }
@@ -58,7 +58,7 @@ func (c *TURN) Verify(configErrs *ConfigErrors) {
 	value := c.UserLifetime
 	if value != "" {
 		if _, err := time.ParseDuration(value); err != nil {
-			configErrs.Add(fmt.Sprintf("invalid duration for config key %q: %s", "client_api.turn.turn_user_lifetime", value))
+			configErrs.Add(fmt.Sprintf("invalid duration for config key %q: %s", "ClientAPI.TURN.TURNUserLifetime", value))
 		}
 	}
 }
diff --git a/internal/config/config_currentstate.go b/internal/config/config_currentstate.go
index 2f47b19e9..f250bb35d 100644
--- a/internal/config/config_currentstate.go
+++ b/internal/config/config_currentstate.go
@@ -3,8 +3,8 @@ package config
 type CurrentStateServer struct {
 	Matrix *Global `json:"-"`
 
-	Listen   Address         `json:"listen" comment:"Listen address for this component."`
-	Bind     Address         `json:"bind" comment:"Bind address for this component."`
+	Listen   Address         `json:"Listen" comment:"Listen address for this component."`
+	Bind     Address         `json:"Bind" comment:"Bind address for this component."`
 	Database DatabaseOptions `json:"Database" comment:"Database configuration for this component."`
 }
 
@@ -16,7 +16,7 @@ func (c *CurrentStateServer) Defaults() {
 }
 
 func (c *CurrentStateServer) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "current_state_server.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "current_state_server.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "current_state_server.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "CurrentStateServer.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "CurrentStateServer.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "CurrentStateServer.Database.ConnectionString", string(c.Database.ConnectionString))
 }
diff --git a/internal/config/config_eduserver.go b/internal/config/config_eduserver.go
index c8001c778..cdb352ec7 100644
--- a/internal/config/config_eduserver.go
+++ b/internal/config/config_eduserver.go
@@ -13,6 +13,6 @@ func (c *EDUServer) Defaults() {
 }
 
 func (c *EDUServer) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "edu_server.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "edu_server.bind", string(c.Bind))
+	checkNotEmpty(configErrs, "EDUServer.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "EDUServer.Bind", string(c.Bind))
 }
diff --git a/internal/config/config_federationapi.go b/internal/config/config_federationapi.go
index e7dfbf76c..7fc3b6da1 100644
--- a/internal/config/config_federationapi.go
+++ b/internal/config/config_federationapi.go
@@ -17,8 +17,8 @@ func (c *FederationAPI) Defaults() {
 }
 
 func (c *FederationAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "federation_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "federation_api.bind", string(c.Bind))
+	checkNotEmpty(configErrs, "FederationAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "FederationAPI.Bind", string(c.Bind))
 	// TODO: not applicable always, e.g. in demos
-	//checkNotZero(configErrs, "federation_api.federation_certificates", int64(len(c.FederationCertificatePaths)))
+	//checkNotZero(configErrs, "FederationAPI.FederationCertificates", int64(len(c.FederationCertificatePaths)))
 }
diff --git a/internal/config/config_federationsender.go b/internal/config/config_federationsender.go
index 973c05148..819dccf31 100644
--- a/internal/config/config_federationsender.go
+++ b/internal/config/config_federationsender.go
@@ -24,9 +24,9 @@ func (c *FederationSender) Defaults() {
 }
 
 func (c *FederationSender) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "federation_sender.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "federation_sender.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "federation_sender.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "FederationSender.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "FederationSender.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "FederationSender.Database.ConnectionString", string(c.Database.ConnectionString))
 }
 
 // The config for setting a proxy to use for server->server requests
diff --git a/internal/config/config_global.go b/internal/config/config_global.go
index ccbfb9c34..1b69c828d 100644
--- a/internal/config/config_global.go
+++ b/internal/config/config_global.go
@@ -31,8 +31,8 @@ func (c *Global) Defaults() {
 }
 
 func (c *Global) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "global.server_name", string(c.ServerName))
-	checkNotEmpty(configErrs, "global.private_key", string(c.PrivateKeyPath))
+	checkNotEmpty(configErrs, "Global.ServerName", string(c.ServerName))
+	checkNotEmpty(configErrs, "Global.PrivateKeyPath", string(c.PrivateKeyPath))
 
 	c.Kafka.Verify(configErrs, isMonolith)
 	c.Metrics.Verify(configErrs, isMonolith)
diff --git a/internal/config/config_kafka.go b/internal/config/config_kafka.go
index 4980d551f..9bc2e31b4 100644
--- a/internal/config/config_kafka.go
+++ b/internal/config/config_kafka.go
@@ -13,7 +13,7 @@ const (
 
 type Kafka struct {
 	Addresses   []string        `json:"Addresses" comment:"List of Kafka addresses to connect to."`
-	TopicPrefix string          `json:"topic_prefix" comment:"The prefix to use for Kafka topic names for this homeserver. Change this only if\nyou are running more than one Dendrite homeserver on the same Kafka deployment."`
+	TopicPrefix string          `json:"TopicPrefix" comment:"The prefix to use for Kafka topic names for this homeserver. Change this only if\nyou are running more than one Dendrite homeserver on the same Kafka deployment."`
 	UseNaffka   bool            `json:"UseNaffka" comment:"Whether to use Naffka instead of Kafka. Only available in monolith mode."`
 	Database    DatabaseOptions `json:"NaffkaDatabase" comment:"Naffka database options. Not required when using Kafka."`
 }
@@ -34,11 +34,11 @@ func (c *Kafka) Verify(configErrs *ConfigErrors, isMonolith bool) {
 		if !isMonolith {
 			configErrs.Add("naffka can only be used in a monolithic server")
 		}
-		checkNotEmpty(configErrs, "global.kafka.database.connection_string", string(c.Database.ConnectionString))
+		checkNotEmpty(configErrs, "Global.Kafka.Database.ConnectionString", string(c.Database.ConnectionString))
 	} else {
 		// If we aren't using naffka then we need to have at least one kafka
 		// server to talk to.
-		checkNotZero(configErrs, "global.kafka.addresses", int64(len(c.Addresses)))
+		checkNotZero(configErrs, "Global.Kafka.Addresses", int64(len(c.Addresses)))
 	}
-	checkNotEmpty(configErrs, "global.kafka.topic_prefix", string(c.TopicPrefix))
+	checkNotEmpty(configErrs, "Global.Kafka.TopicPrefix", string(c.TopicPrefix))
 }
diff --git a/internal/config/config_keyserver.go b/internal/config/config_keyserver.go
index ad0f80af5..2e6c42484 100644
--- a/internal/config/config_keyserver.go
+++ b/internal/config/config_keyserver.go
@@ -16,7 +16,7 @@ func (c *KeyServer) Defaults() {
 }
 
 func (c *KeyServer) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "key_server.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "key_server.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "key_server.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "KeyServer.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "KeyServer.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "KeyServer.Database.ConnectionString", string(c.Database.ConnectionString))
 }
diff --git a/internal/config/config_mediaapi.go b/internal/config/config_mediaapi.go
index 9170a8408..b6af91cb8 100644
--- a/internal/config/config_mediaapi.go
+++ b/internal/config/config_mediaapi.go
@@ -31,16 +31,16 @@ func (c *MediaAPI) Defaults() {
 }
 
 func (c *MediaAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "media_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "media_api.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "media_api.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "MediaAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "MediaAPI.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "MediaAPI.Database.ConnectionString", string(c.Database.ConnectionString))
 
-	checkNotEmpty(configErrs, "media_api.base_path", string(c.BasePath))
-	checkPositive(configErrs, "media_api.max_file_size_bytes", int64(*c.MaxFileSizeBytes))
-	checkPositive(configErrs, "media_api.max_thumbnail_generators", int64(c.MaxThumbnailGenerators))
+	checkNotEmpty(configErrs, "MediaAPI.BasePath", string(c.BasePath))
+	checkPositive(configErrs, "MediaAPI.MaxFileSizeBytes", int64(*c.MaxFileSizeBytes))
+	checkPositive(configErrs, "MediaAPI.MaxThumbnailGenerators", int64(c.MaxThumbnailGenerators))
 
 	for i, size := range c.ThumbnailSizes {
-		checkPositive(configErrs, fmt.Sprintf("media_api.thumbnail_sizes[%d].width", i), int64(size.Width))
-		checkPositive(configErrs, fmt.Sprintf("media_api.thumbnail_sizes[%d].height", i), int64(size.Height))
+		checkPositive(configErrs, fmt.Sprintf("MediaAPI.ThumbnailSizes[%d].Width", i), int64(size.Width))
+		checkPositive(configErrs, fmt.Sprintf("MediaAPI.ThumbnailSizes[%d].Height", i), int64(size.Height))
 	}
 }
diff --git a/internal/config/config_roomserver.go b/internal/config/config_roomserver.go
index 42f858767..268fa86e6 100644
--- a/internal/config/config_roomserver.go
+++ b/internal/config/config_roomserver.go
@@ -16,7 +16,7 @@ func (c *RoomServer) Defaults() {
 }
 
 func (c *RoomServer) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "room_server.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "room_server.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "room_server.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "RoomServer.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "RoomServer.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "RoomServer.Database.ConnectionString", string(c.Database.ConnectionString))
 }
diff --git a/internal/config/config_serverkey.go b/internal/config/config_serverkey.go
index 9ce315502..3e3437aab 100644
--- a/internal/config/config_serverkey.go
+++ b/internal/config/config_serverkey.go
@@ -19,9 +19,9 @@ func (c *ServerKeyAPI) Defaults() {
 }
 
 func (c *ServerKeyAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "server_key_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "server_key_api.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "server_key_api.database.connection_string", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "ServerKeyAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "ServerKeyAPI.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "ServerKeyAPI.Database.ConnectionString", string(c.Database.ConnectionString))
 }
 
 // KeyPerspectives are used to configure perspective key servers for
diff --git a/internal/config/config_syncapi.go b/internal/config/config_syncapi.go
index a2d06aabd..e608cbd84 100644
--- a/internal/config/config_syncapi.go
+++ b/internal/config/config_syncapi.go
@@ -16,7 +16,7 @@ func (c *SyncAPI) Defaults() {
 }
 
 func (c *SyncAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "sync_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "sync_api.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "sync_api.database", string(c.Database.ConnectionString))
+	checkNotEmpty(configErrs, "SyncAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "SyncAPI.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "SyncAPI.Database.ConnectionString", string(c.Database.ConnectionString))
 }
diff --git a/internal/config/config_userapi.go b/internal/config/config_userapi.go
index f01eaf97b..4d117d5d2 100644
--- a/internal/config/config_userapi.go
+++ b/internal/config/config_userapi.go
@@ -19,8 +19,8 @@ func (c *UserAPI) Defaults() {
 }
 
 func (c *UserAPI) Verify(configErrs *ConfigErrors, isMonolith bool) {
-	checkNotEmpty(configErrs, "user_api.listen", string(c.Listen))
-	checkNotEmpty(configErrs, "user_api.bind", string(c.Bind))
-	checkNotEmpty(configErrs, "user_api.account_database.connection_string", string(c.AccountDatabase.ConnectionString))
-	checkNotEmpty(configErrs, "user_api.device_database.connection_string", string(c.DeviceDatabase.ConnectionString))
+	checkNotEmpty(configErrs, "UserAPI.Listen", string(c.Listen))
+	checkNotEmpty(configErrs, "UserAPI.Bind", string(c.Bind))
+	checkNotEmpty(configErrs, "UserAPI.AccountDatabase.ConnectionString", string(c.AccountDatabase.ConnectionString))
+	checkNotEmpty(configErrs, "UserAPI.DeviceDatabase.ConnectionString", string(c.DeviceDatabase.ConnectionString))
 }