diff --git a/api/server.go b/api/server.go
index 0ddfd9a4..d72ba1f0 100644
--- a/api/server.go
+++ b/api/server.go
@@ -74,14 +74,25 @@ const (
 )
 
 var (
-	ErrTransactionNotFound   = errors.New("no transaction found")
-	ErrContractNotFound      = errors.New("no contract found")
+	// ErrTransactionNotFound is returned by /transactions/:id when we are
+	// unable to find the transaction with that `id`.
+	ErrTransactionNotFound = errors.New("no transaction found")
+	// ErrSiacoinOutputNotFound is returned by /outputs/siacoin/:id when we
+	// are unable to find the siacoin output with that `id`.
 	ErrSiacoinOutputNotFound = errors.New("no siacoin output found")
+	// ErrSiafundOutputNotFound is returned by /outputs/siafund/:id when we
+	// are unable to find the siafund output with that `id`.
 	ErrSiafundOutputNotFound = errors.New("no siafund output found")
-	ErrHostNotFound          = errors.New("no host found")
+	// ErrHostNotFound is returned by /pubkey/:key/host when we are unable to
+	// find the host with the pubkey `key`.
+	ErrHostNotFound = errors.New("no host found")
 
-	ErrNoResults = errors.New("no search results found")
+	// ErrNoSearchResults is returned by /search/:id when we do not find any
+	// elements with that ID.
+	ErrNoSearchResults = errors.New("no search results found")
 
+	// ErrTooManyIDs is returned by the batch transaction and contract
+	// endpoints when more than maxIDs IDs are specified.
 	ErrTooManyIDs = fmt.Errorf("too many IDs provided (provide less than %d)", maxIDs)
 )
 
@@ -427,7 +438,7 @@ func (s *server) contractsIDHandler(jc jape.Context) {
 	if jc.Check("failed to get contract", err) != nil {
 		return
 	} else if len(fcs) == 0 {
-		jc.Error(ErrContractNotFound, http.StatusNotFound)
+		jc.Error(explorer.ErrContractNotFound, http.StatusNotFound)
 		return
 	}
 	jc.Encode(fcs[0])
@@ -440,7 +451,7 @@ func (s *server) contractsIDRevisionsHandler(jc jape.Context) {
 	}
 
 	fcs, err := s.e.ContractRevisions(id)
-	if errors.Is(err, ErrContractNotFound) {
+	if errors.Is(err, explorer.ErrContractNotFound) {
 		jc.Error(fmt.Errorf("%w: %v", err, id), http.StatusNotFound)
 		return
 	} else if jc.Check("failed to fetch contract revisions", err) != nil {
@@ -474,7 +485,7 @@ func (s *server) pubkeyContractsHandler(jc jape.Context) {
 	if jc.Check("failed to get contracts", err) != nil {
 		return
 	} else if len(fcs) == 0 {
-		jc.Error(ErrContractNotFound, http.StatusNotFound)
+		jc.Error(explorer.ErrContractNotFound, http.StatusNotFound)
 		return
 	}
 	jc.Encode(fcs)
@@ -510,7 +521,7 @@ func (s *server) searchIDHandler(jc jape.Context) {
 	if jc.Check("failed to search ID", err) != nil {
 		return
 	} else if result == explorer.SearchTypeInvalid {
-		jc.Error(ErrNoResults, http.StatusNotFound)
+		jc.Error(ErrNoSearchResults, http.StatusNotFound)
 		return
 	}
 	jc.Encode(result)