diff --git a/README.md b/README.md
index ba293f0..8ac4b17 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,9 @@ yarn add @stoplight/yaml
 
 ### Usage
 
-- **[parseWithPointers](https://stoplightio.github.io/yaml/globals.html#parsewithpointers)**: Parses YAML into JSON and also returns a source map that includes a JSON path pointer for every property in the result (with line information).
+- **[getJsonPathForPosition](https://stoplightio.github.io/yaml/globals.html#getjsonpathforposition)**: Computes JSON path for given position.
+- **[getLocationForJsonPath](https://stoplightio.github.io/yaml/globals.html#getlocationforjsonpath)**: Retrieves location of node matching given JSON path.
+- **[parseWithPointers](https://stoplightio.github.io/yaml/globals.html#parsewithpointers)**: Parses YAML into JSON and also returns diagnostics as well as full ast with line information.
 
 ```ts
 // basic example of parseWithPointers
@@ -27,7 +29,23 @@ import { parseWithPointers } from "@stoplight/yaml";
 const result = parseWithPointers("foo: bar");
 
 console.log(result.data); // => the {foo: "bar"} JS object
-console.log(result.pointers); // => the source map with a single "#/foo" pointer that has position info for the foo property
+```
+
+```ts
+// basic example of getJsonPathForPosition and getLocationForJsonPath
+import { getJsonPathForPosition, getLocationForJsonPath, parseWithPointers } from "@stoplight/yaml";
+
+const result = parseWithPointers(`hello: world
+address:
+    street: 123`
+);
+
+const path = getJsonPathForPosition(result, { line: 2, character: 7 }); // line and character are 0-based
+console.log(path); // -> ["address", "street"];
+
+const position = getLocationForJsonPath(result, ['address']);
+console.log(position.range.start); // { line: 1, character: 8 } line and character are 0-based
+console.log(position.range.end); // { line: 2, character: 15 } line and character are 0-based
 ```
 
 ### Contributing
diff --git a/src/__tests__/parseWithPointers.spec.ts b/src/__tests__/parseWithPointers.spec.ts
index 977bbe4..d227d10 100644
--- a/src/__tests__/parseWithPointers.spec.ts
+++ b/src/__tests__/parseWithPointers.spec.ts
@@ -43,45 +43,91 @@ describe('yaml parser', () => {
     expect(result.data).toEqual(HugeJSON);
   });
 
-  test('report errors', () => {
-    const result = parseWithPointers(
-      `prop1: true
+  describe('report errors', () => {
+    test('unknown tags', () => {
+      const result = parseWithPointers(`function: !!js/function >
+  function foobar() {
+    return 'Wow! JS-YAML Rocks!';
+  }
+  
+test: !!css >
+  function boom() {}
+`);
+
+      expect(result).toHaveProperty('diagnostics', [
+        {
+          code: 'YAMLException',
+          message: 'unknown tag <tag:yaml.org,2002:js/function>',
+          range: {
+            end: {
+              character: 25,
+              line: 0,
+            },
+            start: {
+              character: 10,
+              line: 0,
+            },
+          },
+          severity: DiagnosticSeverity.Error,
+        },
+        {
+          code: 'YAMLException',
+          message: 'unknown tag <tag:yaml.org,2002:css>',
+          range: {
+            end: {
+              character: 13,
+              line: 5,
+            },
+            start: {
+              character: 6,
+              line: 5,
+            },
+          },
+          severity: DiagnosticSeverity.Error,
+        },
+      ]);
+    });
+
+    test('invalid mapping', () => {
+      const result = parseWithPointers(
+        `prop1: true
 prop2: true
   inner 1
   val: 2`
-    );
+      );
 
-    expect(result.diagnostics).toEqual([
-      {
-        severity: DiagnosticSeverity.Error,
-        message: 'bad indentation of a mapping entry',
-        code: 'YAMLException',
-        range: {
-          start: {
-            character: 5,
-            line: 2,
-          },
-          end: {
-            character: 5,
-            line: 2,
+      expect(result.diagnostics).toEqual([
+        {
+          severity: DiagnosticSeverity.Error,
+          message: 'bad indentation of a mapping entry',
+          code: 'YAMLException',
+          range: {
+            start: {
+              character: 5,
+              line: 3,
+            },
+            end: {
+              character: 5,
+              line: 3,
+            },
           },
         },
-      },
-      {
-        severity: DiagnosticSeverity.Error,
-        message: 'incomplete explicit mapping pair; a key node is missed',
-        code: 'YAMLException',
-        range: {
-          start: {
-            character: 7,
-            line: 2,
-          },
-          end: {
-            character: 7,
-            line: 2,
+        {
+          severity: DiagnosticSeverity.Error,
+          message: 'incomplete explicit mapping pair; a key node is missed',
+          code: 'YAMLException',
+          range: {
+            start: {
+              character: 7,
+              line: 3,
+            },
+            end: {
+              character: 7,
+              line: 3,
+            },
           },
         },
-      },
-    ]);
+      ]);
+    });
   });
 });
diff --git a/src/parseWithPointers.ts b/src/parseWithPointers.ts
index d9b6973..e781c73 100644
--- a/src/parseWithPointers.ts
+++ b/src/parseWithPointers.ts
@@ -81,6 +81,14 @@ const computeLineMap = (input: string) => {
   return lineMap;
 };
 
+function getLineLength(lineMap: number[], line: number) {
+  if (line === 0) {
+    return Math.max(0, lineMap[0] - 1);
+  }
+
+  return Math.max(0, lineMap[line] - lineMap[line - 1] - 1);
+}
+
 const transformErrors = (errors: YAMLException[], lineMap: number[]): IDiagnostic[] => {
   const validations: IDiagnostic[] = [];
   for (const error of errors) {
@@ -90,12 +98,12 @@ const transformErrors = (errors: YAMLException[], lineMap: number[]): IDiagnosti
       severity: error.isWarning ? DiagnosticSeverity.Warning : DiagnosticSeverity.Error,
       range: {
         start: {
-          line: error.mark.line - 1,
+          line: error.mark.line,
           character: error.mark.column,
         },
         end: {
-          line: error.mark.line - 1,
-          character: error.mark.toLineEnd ? lineMap[error.mark.line - 1] : error.mark.column,
+          line: error.mark.line,
+          character: error.mark.toLineEnd ? getLineLength(lineMap, error.mark.line) : error.mark.column,
         },
       },
     };