diff --git a/cmd/indexer/main.go b/cmd/indexer/main.go
index 93aa69a..8d5c159 100644
--- a/cmd/indexer/main.go
+++ b/cmd/indexer/main.go
@@ -170,8 +170,8 @@ func runIndexer(chains []string, configPath string, debug, manual, catchup, from
 
 	// If no chains specified, use all configured chains
 	if len(chains) == 0 {
-		chains = cfg.Chains.Names()
-		logger.Info("No chains specified, using all configured chains", "chains", chains)
+		chains = cfg.Chains.EnabledNames()
+		logger.Info("No chains specified, using enabled configured chains", "chains", chains)
 	} else {
 		logger.Info("Indexing specified chains", "chains", chains)
 	}
diff --git a/configs/config.example.yaml b/configs/config.example.yaml
index 8b9e6dc..81fa271 100644
--- a/configs/config.example.yaml
+++ b/configs/config.example.yaml
@@ -4,6 +4,7 @@ version: "1.0.0"
 
 # Global defaults - applies to all chains unless overridden
 defaults:
+  enabled: false # chains inherit this unless they override enabled below
   from_latest: true # start indexing from the latest block
   poll_interval: "5s" # how often to poll for new blocks
   reorg_rollback_window: 20 # number of blocks to roll back on reorg
@@ -47,6 +48,7 @@ chains:
       slow_max_pending_blocks: 400
 
   ethereum_mainnet:
+    enabled: true # example override: this chain starts even when defaults.enabled is false
     network_id: "ethereum_mainnet"
     internal_code: "ETH_MAINNET"
     type: "evm"
diff --git a/pkg/common/config/chains.go b/pkg/common/config/chains.go
index 505e032..ce81537 100644
--- a/pkg/common/config/chains.go
+++ b/pkg/common/config/chains.go
@@ -31,6 +31,17 @@ func (c Chains) Names() []string {
 	return names
 }
 
+// EnabledNames returns chain names whose enabled flag is either true or omitted.
+func (c Chains) EnabledNames() []string {
+	names := make([]string, 0, len(c))
+	for k, chain := range c {
+		if chain.Enabled == nil || *chain.Enabled {
+			names = append(names, k)
+		}
+	}
+	return names
+}
+
 // Validate checks if given chain names exist in config.
 func (c Chains) Validate(names []string) error {
 	for _, name := range names {
@@ -60,6 +71,10 @@ func (c Chains) ApplyDefaults(def Defaults) error {
 		if strings.TrimSpace(chain.InternalCode) == "" {
 			chain.InternalCode = strings.ToUpper(name)
 		}
+		if chain.Enabled == nil && def.Enabled != nil {
+			enabled := *def.Enabled
+			chain.Enabled = &enabled
+		}
 		if !chain.FromLatest {
 			chain.FromLatest = def.FromLatest
 		}
diff --git a/pkg/common/config/chains_test.go b/pkg/common/config/chains_test.go
index fb9fea3..0e65cee 100644
--- a/pkg/common/config/chains_test.go
+++ b/pkg/common/config/chains_test.go
@@ -36,3 +36,91 @@ func TestApplyDefaults_MergesStatusThresholds(t *testing.T) {
 	require.Equal(t, uint64(30), chain.Status.HealthyMaxPendingBlocks)
 	require.Equal(t, uint64(120), chain.Status.SlowMaxPendingBlocks)
 }
+
+func TestApplyDefaults_AppliesEnabledDefaultWhenOmitted(t *testing.T) {
+	t.Parallel()
+
+	enabled := false
+	chains := Chains{
+		"ethereum_mainnet": {
+			Type:         enum.NetworkTypeEVM,
+			PollInterval: time.Second,
+			Nodes:        []NodeConfig{{URL: "https://example.com"}},
+		},
+	}
+
+	err := chains.ApplyDefaults(Defaults{
+		Enabled:             &enabled,
+		PollInterval:        time.Second,
+		ReorgRollbackWindow: 20,
+	})
+	require.NoError(t, err)
+
+	require.NotNil(t, chains["ethereum_mainnet"].Enabled)
+	require.False(t, *chains["ethereum_mainnet"].Enabled)
+}
+
+func TestApplyDefaults_PreservesExplicitEnabledValue(t *testing.T) {
+	t.Parallel()
+
+	defaultEnabled := false
+	chainEnabled := true
+	chains := Chains{
+		"ethereum_mainnet": {
+			Enabled:      &chainEnabled,
+			Type:         enum.NetworkTypeEVM,
+			PollInterval: time.Second,
+			Nodes:        []NodeConfig{{URL: "https://example.com"}},
+		},
+	}
+
+	err := chains.ApplyDefaults(Defaults{
+		Enabled:             &defaultEnabled,
+		PollInterval:        time.Second,
+		ReorgRollbackWindow: 20,
+	})
+	require.NoError(t, err)
+
+	require.NotNil(t, chains["ethereum_mainnet"].Enabled)
+	require.True(t, *chains["ethereum_mainnet"].Enabled)
+}
+
+func TestEnabledNames_DefaultsToEnabledWhenOmitted(t *testing.T) {
+	t.Parallel()
+
+	disabled := false
+	chains := Chains{
+		"ethereum_mainnet": {
+			Type:  enum.NetworkTypeEVM,
+			Nodes: []NodeConfig{{URL: "https://example.com"}},
+		},
+		"tron_mainnet": {
+			Enabled: &disabled,
+			Type:    enum.NetworkTypeTron,
+			Nodes:   []NodeConfig{{URL: "https://example.com"}},
+		},
+	}
+
+	require.ElementsMatch(t, []string{"ethereum_mainnet"}, chains.EnabledNames())
+}
+
+func TestEnabledNames_IncludesExplicitlyEnabledChains(t *testing.T) {
+	t.Parallel()
+
+	enabled := true
+	disabled := false
+	chains := Chains{
+		"ethereum_mainnet": {
+			Enabled: &enabled,
+			Type:    enum.NetworkTypeEVM,
+			Nodes:   []NodeConfig{{URL: "https://example.com"}},
+		},
+		"tron_mainnet": {
+			Enabled: &disabled,
+			Type:    enum.NetworkTypeTron,
+			Nodes:   []NodeConfig{{URL: "https://example.com"}},
+		},
+	}
+
+	require.ElementsMatch(t, []string{"ethereum_mainnet"}, chains.EnabledNames())
+}
diff --git a/pkg/common/config/types.go b/pkg/common/config/types.go
index 510c102..fd41a7c 100644
--- a/pkg/common/config/types.go
+++ b/pkg/common/config/types.go
@@ -28,6 +28,7 @@ type Config struct {
 }
 
 type Defaults struct {
+	Enabled             *bool              `yaml:"enabled"`
 	FromLatest          bool               `yaml:"from_latest"`
 	TwoWayIndexing      bool               `yaml:"two_way_indexing"`
 	PollInterval        time.Duration      `yaml:"poll_interval"         validate:"required"`
@@ -42,6 +43,7 @@ type Chains map[string]ChainConfig
 
 type ChainConfig struct {
 	Name                string           `yaml:"-"`
+	Enabled             *bool            `yaml:"enabled"`
 	NetworkId           string           `yaml:"network_id"`
 	InternalCode        string           `yaml:"internal_code"`
 	NativeDenom         string           `yaml:"native_denom"`