diff --git a/api/api_full.go b/api/api_full.go
index bb1eb159540..0b9fb71d241 100644
--- a/api/api_full.go
+++ b/api/api_full.go
@@ -344,6 +344,8 @@ type FullNode interface {
 	StateReadState(ctx context.Context, actor address.Address, tsk types.TipSetKey) (*ActorState, error)
 	// StateListMessages looks back and returns all messages with a matching to or from address, stopping at the given height.
 	StateListMessages(ctx context.Context, match *MessageMatch, tsk types.TipSetKey, toht abi.ChainEpoch) ([]cid.Cid, error)
+	// StateDecodeParams attempts to decode the provided params, based on the recipient actor address and method number.
+	StateDecodeParams(ctx context.Context, toAddr address.Address, method abi.MethodNum, params []byte, tsk types.TipSetKey) (interface{}, error)
 
 	// StateNetworkName returns the name of the network the node is synced to
 	StateNetworkName(context.Context) (dtypes.NetworkName, error)
diff --git a/api/apistruct/struct.go b/api/apistruct/struct.go
index 3a4ae75a8f3..35f279c3d6a 100644
--- a/api/apistruct/struct.go
+++ b/api/apistruct/struct.go
@@ -215,6 +215,7 @@ type FullNodeStruct struct {
 		StateGetReceipt                    func(context.Context, cid.Cid, types.TipSetKey) (*types.MessageReceipt, error)                                      `perm:"read"`
 		StateMinerSectorCount              func(context.Context, address.Address, types.TipSetKey) (api.MinerSectors, error)                                   `perm:"read"`
 		StateListMessages                  func(ctx context.Context, match *api.MessageMatch, tsk types.TipSetKey, toht abi.ChainEpoch) ([]cid.Cid, error)     `perm:"read"`
+		StateDecodeParams                  func(context.Context, address.Address, abi.MethodNum, []byte, types.TipSetKey) (interface{}, error)                 `perm:"read"`
 		StateCompute                       func(context.Context, abi.ChainEpoch, []*types.Message, types.TipSetKey) (*api.ComputeStateOutput, error)           `perm:"read"`
 		StateVerifierStatus                func(context.Context, address.Address, types.TipSetKey) (*abi.StoragePower, error)                                  `perm:"read"`
 		StateVerifiedClientStatus          func(context.Context, address.Address, types.TipSetKey) (*abi.StoragePower, error)                                  `perm:"read"`
@@ -1014,6 +1015,10 @@ func (c *FullNodeStruct) StateListMessages(ctx context.Context, match *api.Messa
 	return c.Internal.StateListMessages(ctx, match, tsk, toht)
 }
 
+func (c *FullNodeStruct) StateDecodeParams(ctx context.Context, toAddr address.Address, method abi.MethodNum, params []byte, tsk types.TipSetKey) (interface{}, error) {
+	return c.Internal.StateDecodeParams(ctx, toAddr, method, params, tsk)
+}
+
 func (c *FullNodeStruct) StateCompute(ctx context.Context, height abi.ChainEpoch, msgs []*types.Message, tsk types.TipSetKey) (*api.ComputeStateOutput, error) {
 	return c.Internal.StateCompute(ctx, height, msgs, tsk)
 }
diff --git a/chain/stmgr/utils.go b/chain/stmgr/utils.go
index 5b144281d53..78121cc4c52 100644
--- a/chain/stmgr/utils.go
+++ b/chain/stmgr/utils.go
@@ -614,6 +614,14 @@ func GetReturnType(ctx context.Context, sm *StateManager, to address.Address, me
 	return reflect.New(m.Ret.Elem()).Interface().(cbg.CBORUnmarshaler), nil
 }
 
+func GetParamType(actCode cid.Cid, method abi.MethodNum) (cbg.CBORUnmarshaler, error) {
+	m, found := MethodsMap[actCode][method]
+	if !found {
+		return nil, fmt.Errorf("unknown method %d for actor %s", method, actCode)
+	}
+	return reflect.New(m.Params.Elem()).Interface().(cbg.CBORUnmarshaler), nil
+}
+
 func minerHasMinPower(ctx context.Context, sm *StateManager, addr address.Address, ts *types.TipSet) (bool, error) {
 	pact, err := sm.LoadActor(ctx, power.Address, ts)
 	if err != nil {
diff --git a/cli/state.go b/cli/state.go
index 13aa5c39b8c..c17a4f438ba 100644
--- a/cli/state.go
+++ b/cli/state.go
@@ -1299,12 +1299,11 @@ func sumGas(changes []*types.GasTrace) types.GasTrace {
 }
 
 func JsonParams(code cid.Cid, method abi.MethodNum, params []byte) (string, error) {
-	methodMeta, found := stmgr.MethodsMap[code][method]
-	if !found {
-		return "", fmt.Errorf("method %d not found on actor %s", method, code)
+	p, err := stmgr.GetParamType(code, method)
+	if err != nil {
+		return "", err
 	}
-	re := reflect.New(methodMeta.Params.Elem())
-	p := re.Interface().(cbg.CBORUnmarshaler)
+
 	if err := p.UnmarshalCBOR(bytes.NewReader(params)); err != nil {
 		return "", err
 	}
diff --git a/documentation/en/api-methods.md b/documentation/en/api-methods.md
index 4e18d85c919..4ab89d688fe 100644
--- a/documentation/en/api-methods.md
+++ b/documentation/en/api-methods.md
@@ -140,6 +140,7 @@
   * [StateCirculatingSupply](#StateCirculatingSupply)
   * [StateCompute](#StateCompute)
   * [StateDealProviderCollateralBounds](#StateDealProviderCollateralBounds)
+  * [StateDecodeParams](#StateDecodeParams)
   * [StateGetActor](#StateGetActor)
   * [StateGetReceipt](#StateGetReceipt)
   * [StateListActors](#StateListActors)
@@ -3387,6 +3388,31 @@ Response:
 }
 ```
 
+### StateDecodeParams
+StateDecodeParams attempts to decode the provided params, based on the recipient actor address and method number.
+
+
+Perms: read
+
+Inputs:
+```json
+[
+  "f01234",
+  1,
+  "Ynl0ZSBhcnJheQ==",
+  [
+    {
+      "/": "bafy2bzacea3wsdh6y3a36tb3skempjoxqpuyompjbmfeyf34fi3uy6uue42v4"
+    },
+    {
+      "/": "bafy2bzacebp3shtrn43k7g3unredz7fxn4gj533d3o43tqn2p2ipxxhrvchve"
+    }
+  ]
+]
+```
+
+Response: `{}`
+
 ### StateGetActor
 StateGetActor returns the indicated actor's nonce and balance.
 
diff --git a/node/impl/full/state.go b/node/impl/full/state.go
index 9a6c772ae3c..126ff0d7bb7 100644
--- a/node/impl/full/state.go
+++ b/node/impl/full/state.go
@@ -491,6 +491,24 @@ func (a *StateAPI) StateReadState(ctx context.Context, actor address.Address, ts
 	}, nil
 }
 
+func (a *StateAPI) StateDecodeParams(ctx context.Context, toAddr address.Address, method abi.MethodNum, params []byte, tsk types.TipSetKey) (interface{}, error) {
+	act, err := a.StateGetActor(ctx, toAddr, tsk)
+	if err != nil {
+		return nil, xerrors.Errorf("getting actor: %w", err)
+	}
+
+	paramType, err := stmgr.GetParamType(act.Code, method)
+	if err != nil {
+		return nil, xerrors.Errorf("getting params type: %w", err)
+	}
+
+	if err = paramType.UnmarshalCBOR(bytes.NewReader(params)); err != nil {
+		return nil, err
+	}
+
+	return paramType, nil
+}
+
 // This is on StateAPI because miner.Miner requires this, and MinerAPI requires miner.Miner
 func (a *StateAPI) MinerGetBaseInfo(ctx context.Context, maddr address.Address, epoch abi.ChainEpoch, tsk types.TipSetKey) (*api.MiningBaseInfo, error) {
 	return stmgr.MinerGetBaseInfo(ctx, a.StateManager, a.Beacon, tsk, epoch, maddr, a.ProofVerifier)