diff --git a/examples/gno.land/r/demo/teritori/projects_manager/filter.gno b/examples/gno.land/r/demo/teritori/projects_manager/filter.gno
new file mode 100644
index 00000000000..0d727f3353d
--- /dev/null
+++ b/examples/gno.land/r/demo/teritori/projects_manager/filter.gno
@@ -0,0 +1,81 @@
+package projects_manager
+
+import (
+	"std"
+
+	"gno.land/p/demo/dao_maker/jsonutil"
+	"gno.land/p/demo/json"
+	"gno.land/p/demo/ufmt"
+)
+
+type Filter interface {
+	FromJSON(ast *json.Node)
+}
+
+func FilterFromJSON(ast *json.Node) Filter {
+	if ast.IsNull() {
+		return nil
+	}
+	var filter Filter
+	key, member := jsonutil.MustUnion(ast)
+	switch key {
+	case "byCandidatesForFunder":
+		filter = &FilterByCandidatesForFunder{}
+	case "byFunder":
+		filter = &FilterByFunder{}
+	case "byContractor":
+		filter = &FilterByContractor{}
+	case "byContractorAndFunder":
+		filter = &FilterByContractorAndFunder{}
+	default:
+		panic(ufmt.Sprintf("invalid filter kind `%s`", key))
+	}
+	filter.FromJSON(member)
+	return filter
+}
+
+type FilterByCandidatesForFunder struct {
+	Funder std.Address
+}
+
+func (f *FilterByCandidatesForFunder) FromJSON(ast *json.Node) {
+	obj := ast.MustObject()
+	f.Funder = jsonutil.MustAddress(obj["funder"])
+}
+
+var _ Filter = &FilterByCandidatesForFunder{}
+
+type FilterByFunder struct {
+	Funder std.Address
+}
+
+func (f *FilterByFunder) FromJSON(ast *json.Node) {
+	obj := ast.MustObject()
+	f.Funder = jsonutil.MustAddress(obj["funder"])
+}
+
+var _ Filter = &FilterByFunder{}
+
+type FilterByContractor struct {
+	Contractor std.Address
+}
+
+func (f *FilterByContractor) FromJSON(ast *json.Node) {
+	obj := ast.MustObject()
+	f.Contractor = jsonutil.MustAddress(obj["contractor"])
+}
+
+var _ Filter = &FilterByContractor{}
+
+type FilterByContractorAndFunder struct {
+	Contractor std.Address
+	Funder     std.Address
+}
+
+func (f *FilterByContractorAndFunder) FromJSON(ast *json.Node) {
+	obj := ast.MustObject()
+	f.Contractor = jsonutil.MustAddress(obj["contractor"])
+	f.Funder = jsonutil.MustAddress(obj["funder"])
+}
+
+var _ Filter = &FilterByContractorAndFunder{}
diff --git a/examples/gno.land/r/demo/teritori/projects_manager/projects_manager.gno b/examples/gno.land/r/demo/teritori/projects_manager/projects_manager.gno
index 756def95f21..ff3da646d6f 100644
--- a/examples/gno.land/r/demo/teritori/projects_manager/projects_manager.gno
+++ b/examples/gno.land/r/demo/teritori/projects_manager/projects_manager.gno
@@ -275,6 +275,7 @@ var (
 	contractsByFunder              = avl.NewTree() // std.Address(funder) => contractID => *Contract
 	contractsByContractor          = avl.NewTree() // std.Address(contractor) => contractID => *Contract
 	contractsByFunderAndContractor = avl.NewTree() // std.Address(funder) + std.Address(contractor) => contractID => *Contract
+	contractsWithCandidates        = avl.NewTree() // std.Address(funder) => contractID => *Contract
 )
 
 func setIndices(contract *Contract) {
@@ -578,6 +579,18 @@ func AcceptContractor(contractId uint64, contractor std.Address) {
 	}
 
 	contracts[contractId].contractor = contractor
+
+	funderKey := contract.funder.String()
+	byIDTreeIface, ok := contractsWithCandidates.Get(funderKey)
+	if !ok {
+		byIDTreeIface = avl.NewTree()
+		contractsWithCandidates.Set(funderKey, byIDTreeIface)
+	}
+	byIDTree := byIDTreeIface.(*avl.Tree)
+	byIDTree.Remove(seqid.ID(contract.id).String())
+	if byIDTree.Size() == 0 {
+		contractsWithCandidates.Remove(funderKey)
+	}
 }
 
 func SubmitContractorCandidate(contractId uint64) {
@@ -608,6 +621,14 @@ func SubmitContractorCandidate(contractId uint64) {
 	}
 
 	contracts[contractId].contractorCandidates = append(candidates, caller)
+
+	funderKey := contract.funder.String()
+	byIDTree, ok := contractsWithCandidates.Get(funderKey)
+	if !ok {
+		byIDTree = avl.NewTree()
+		contractsWithCandidates.Set(funderKey, byIDTree)
+	}
+	byIDTree.(*avl.Tree).Set(seqid.ID(contract.id).String(), contract)
 }
 
 // Complete any milestone in review status and pay the needed amount
@@ -822,7 +843,7 @@ func GetContractorCandidatesJSON(contractId uint64) string {
 	return string(ret)
 }
 
-func GetContracts(offset, limit int, filterByFunder string, filterByContractor string) []*Contract {
+func GetContracts(offset, limit int, filter Filter) []*Contract {
 	if offset < 0 {
 		offset = 0
 	}
@@ -831,14 +852,7 @@ func GetContracts(offset, limit int, filterByFunder string, filterByContractor s
 		return nil
 	}
 
-	var tree interface{}
-	if filterByFunder != "" && filterByContractor != "" {
-		tree, _ = contractsByFunderAndContractor.Get(filterByFunder + filterByContractor)
-	} else if filterByFunder != "" {
-		tree, _ = contractsByFunder.Get(filterByFunder)
-	} else if filterByContractor != "" {
-		tree, _ = contractsByContractor.Get(filterByContractor)
-	} else {
+	if filter == nil {
 		end := offset + limit
 		if end > len(contracts) {
 			end = len(contracts)
@@ -846,6 +860,20 @@ func GetContracts(offset, limit int, filterByFunder string, filterByContractor s
 		return contracts[offset:end]
 	}
 
+	var tree interface{}
+	switch f := filter.(type) {
+	case *FilterByCandidatesForFunder:
+		tree, _ = contractsWithCandidates.Get(f.Funder.String())
+	case *FilterByContractorAndFunder:
+		tree, _ = contractsByFunderAndContractor.Get(f.Funder.String() + f.Contractor.String())
+	case *FilterByContractor:
+		tree, _ = contractsByContractor.Get(f.Contractor.String())
+	case *FilterByFunder:
+		tree, _ = contractsByFunder.Get(f.Funder.String())
+	default:
+		panic("unknown filter")
+	}
+
 	if tree == nil {
 		return nil
 	}
@@ -873,10 +901,15 @@ func RenderContractJSON(contractId uint64) string {
 	return string(ret)
 }
 
-func RenderContractsJSON(offset, limit int, filterByFunder string, filterByContractor string) string {
-	contracts := GetContracts(offset, limit, filterByFunder, filterByContractor)
-	contractsJSON := make([]*json.Node, len(contracts))
-	for i, c := range contracts {
+func RenderContractsJSON(offset, limit int, filterJSON string) string {
+	filter := FilterFromJSON(json.Must(json.Unmarshal([]byte(filterJSON))))
+	contractsRes := GetContracts(offset, limit, filter)
+	return renderContractsJSON(contractsRes)
+}
+
+func renderContractsJSON(contractsRes []*Contract) string {
+	contractsJSON := make([]*json.Node, len(contractsRes))
+	for i, c := range contractsRes {
 		contractsJSON[i] = c.ToJSON()
 	}