diff --git a/packages/gatsby/src/redux/__tests__/__snapshots__/nodes.js.snap b/packages/gatsby/src/redux/__tests__/__snapshots__/nodes.ts.snap
similarity index 100%
rename from packages/gatsby/src/redux/__tests__/__snapshots__/nodes.js.snap
rename to packages/gatsby/src/redux/__tests__/__snapshots__/nodes.ts.snap
diff --git a/packages/gatsby/src/redux/__tests__/nodes.js b/packages/gatsby/src/redux/__tests__/nodes.ts
similarity index 83%
rename from packages/gatsby/src/redux/__tests__/nodes.js
rename to packages/gatsby/src/redux/__tests__/nodes.ts
index 44870361eac3a..80f73686f3044 100644
--- a/packages/gatsby/src/redux/__tests__/nodes.js
+++ b/packages/gatsby/src/redux/__tests__/nodes.ts
@@ -1,18 +1,29 @@
-const { actions } = require(`../actions`)
-const nodeReducer = require(`../reducers/nodes`)
-const nodeTouchedReducer = require(`../reducers/nodes-touched`)
+import { actions } from "../actions"
+import { nodeReducer } from "../reducers/nodes"
+import nodeTouchedReducer from "../reducers/nodes-touched"
+import { IGatsbyNode } from "../types"
 
 jest.mock(`../../db/nodes`)
 jest.mock(`../nodes`)
 
 const dispatch = jest.fn()
 
-describe(`Create and update nodes`, () => {
-  beforeEach(() => {
+type MapObject = Record<string, IGatsbyNode>
+
+const fromMapToObject = (map: Map<string, any>): MapObject => {
+  const obj: MapObject = {}
+  Array.from(map.entries()).forEach(([key, value]) => {
+    obj[key] = value
+  })
+  return obj
+}
+
+describe(`Create and update nodes`, (): void => {
+  beforeEach((): void => {
     dispatch.mockClear()
   })
 
-  it(`allows creating nodes`, () => {
+  it(`allows creating nodes`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -37,7 +48,7 @@ describe(`Create and update nodes`, () => {
     })
   })
 
-  it(`allows updating nodes`, () => {
+  it(`allows updating nodes`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -89,12 +100,13 @@ describe(`Create and update nodes`, () => {
 
     let state = nodeReducer(undefined, action)
     state = nodeReducer(state, updateAction)
-    expect(state.get(`hi`).pickle).toEqual(false)
-    expect(state.get(`hi`).deep.array[0]).toEqual(1)
-    expect(state.get(`hi`).deep2.boom).toEqual(`foo`)
+
+    expect(state.get(`hi`)!.pickle).toEqual(false)
+    expect((state.get(`hi`)!.deep as any).array![0]).toEqual(1)
+    expect((state.get(`hi`)!.deep2 as any).boom).toEqual(`foo`)
   })
 
-  it(`nodes that are added are also "touched"`, () => {
+  it(`nodes that are added are also "touched"`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -112,14 +124,14 @@ describe(`Create and update nodes`, () => {
     )(dispatch)
     const action = dispatch.mock.calls[0][0]
 
-    let state = nodeTouchedReducer(undefined, action)
+    const state = nodeTouchedReducer(undefined, action)
 
     expect(state instanceof Set).toBe(true)
 
     expect(state.has(`hi`)).toBe(true)
   })
 
-  it(`allows adding fields to nodes`, () => {
+  it(`allows adding fields to nodes`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -155,7 +167,7 @@ describe(`Create and update nodes`, () => {
     })
   })
 
-  it(`throws error if a field is updated by a plugin not its owner`, () => {
+  it(`throws error if a field is updated by a plugin not its owner`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -186,7 +198,7 @@ describe(`Create and update nodes`, () => {
     )
     state = nodeReducer(state, addFieldAction)
 
-    function callActionCreator() {
+    function callActionCreator(): void {
       actions.createNodeField(
         {
           node: state.get(`hi`),
@@ -203,7 +215,7 @@ describe(`Create and update nodes`, () => {
     )
   })
 
-  it(`throws error if a node is created by a plugin not its owner`, () => {
+  it(`throws error if a node is created by a plugin not its owner`, (): void => {
     actions.createNode(
       {
         id: `hi`,
@@ -220,7 +232,7 @@ describe(`Create and update nodes`, () => {
       }
     )(dispatch)
 
-    function callActionCreator() {
+    function callActionCreator(): void {
       actions.createNode(
         {
           id: `hi2`,
@@ -243,8 +255,8 @@ describe(`Create and update nodes`, () => {
     )
   })
 
-  it(`throws error if a node sets a value on "fields"`, () => {
-    function callActionCreator() {
+  it(`throws error if a node sets a value on "fields"`, (): void => {
+    function callActionCreator(): void {
       actions.createNode(
         {
           id: `hi`,
@@ -271,11 +283,3 @@ describe(`Create and update nodes`, () => {
     )
   })
 })
-
-const fromMapToObject = map => {
-  const obj = {}
-  Array.from(map.entries()).forEach(([key, value]) => {
-    obj[key] = value
-  })
-  return obj
-}
diff --git a/packages/gatsby/src/redux/reducers/index.js b/packages/gatsby/src/redux/reducers/index.js
index db80119a10f52..10223e20f2458 100644
--- a/packages/gatsby/src/redux/reducers/index.js
+++ b/packages/gatsby/src/redux/reducers/index.js
@@ -1,4 +1,4 @@
-const reduxNodes = require(`./nodes`)
+import { nodeReducer } from "./nodes"
 const lokiNodes = require(`../../db/loki/nodes`).reducer
 import { pagesReducer } from "./pages"
 import { redirectsReducer } from "./redirects"
@@ -10,6 +10,7 @@ import { pageDataReducer } from "./page-data"
 import { themesReducer } from "./themes"
 import { webpackCompilationHashReducer } from "./webpack-compilation-hash"
 import { reducer as logReducer } from "gatsby-cli/lib/reporter/redux/reducer"
+import { lastAction } from "./last-action"
 
 // const backend = process.env.GATSBY_DB_NODES || `redux`
 const backend = `redux`
@@ -18,7 +19,7 @@ function getNodesReducer() {
   let nodesReducer
   switch (backend) {
     case `redux`:
-      nodesReducer = reduxNodes
+      nodesReducer = nodeReducer
       break
     case `loki`:
       nodesReducer = lokiNodes
@@ -57,7 +58,7 @@ module.exports = {
   nodesByType: getNodesByTypeReducer(),
   resolvedNodesCache: require(`./resolved-nodes`),
   nodesTouched: require(`./nodes-touched`),
-  lastAction: require(`./last-action`),
+  lastAction: lastAction,
   flattenedPlugins: require(`./flattened-plugins`),
   config: require(`./config`),
   schema: schemaReducer,
diff --git a/packages/gatsby/src/redux/reducers/last-action.js b/packages/gatsby/src/redux/reducers/last-action.js
deleted file mode 100644
index 7f6a486f36394..0000000000000
--- a/packages/gatsby/src/redux/reducers/last-action.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = (state = null, action) => action
diff --git a/packages/gatsby/src/redux/reducers/last-action.ts b/packages/gatsby/src/redux/reducers/last-action.ts
new file mode 100644
index 0000000000000..1b3b11c756cf0
--- /dev/null
+++ b/packages/gatsby/src/redux/reducers/last-action.ts
@@ -0,0 +1,6 @@
+import { IGatsbyState, ActionsUnion } from "../types"
+
+export const lastAction = (
+  _state: IGatsbyState["lastAction"],
+  action: ActionsUnion
+): IGatsbyState["lastAction"] => action
diff --git a/packages/gatsby/src/redux/reducers/nodes.js b/packages/gatsby/src/redux/reducers/nodes.ts
similarity index 76%
rename from packages/gatsby/src/redux/reducers/nodes.js
rename to packages/gatsby/src/redux/reducers/nodes.ts
index 2e37dd3a16b56..d9ee830706a12 100644
--- a/packages/gatsby/src/redux/reducers/nodes.js
+++ b/packages/gatsby/src/redux/reducers/nodes.ts
@@ -1,7 +1,13 @@
-module.exports = (state = new Map(), action) => {
+import { ActionsUnion, IGatsbyState } from "../types"
+
+export const nodeReducer = (
+  state: IGatsbyState["nodes"] = new Map(),
+  action: ActionsUnion
+): IGatsbyState["nodes"] => {
   switch (action.type) {
     case `DELETE_CACHE`:
       return new Map()
+
     case `CREATE_NODE`: {
       state.set(action.payload.id, action.payload)
       return state
diff --git a/packages/gatsby/src/redux/types.ts b/packages/gatsby/src/redux/types.ts
index fc0ea0dfc7080..569ceea30e911 100644
--- a/packages/gatsby/src/redux/types.ts
+++ b/packages/gatsby/src/redux/types.ts
@@ -223,12 +223,17 @@ export interface ICachedReduxState {
 }
 
 export type ActionsUnion =
+  | IAddChildNodeToParentNodeAction
+  | IAddFieldToNodeAction
   | IAddThirdPartySchema
   | ICreateFieldExtension
+  | ICreateNodeAction
   | ICreatePageAction
   | ICreatePageDependencyAction
   | ICreateTypes
   | IDeleteCacheAction
+  | IDeleteNodeAction
+  | IDeleteNodesAction
   | IDeleteComponentDependenciesAction
   | IDeletePageAction
   | IPageQueryRunAction
@@ -472,3 +477,30 @@ export interface ISetSiteConfig {
   type: `SET_SITE_CONFIG`
   payload: IGatsbyState["config"]
 }
+
+export interface ICreateNodeAction {
+  type: `CREATE_NODE`
+  payload: IGatsbyNode
+}
+
+export interface IAddFieldToNodeAction {
+  type: `ADD_FIELD_TO_NODE`
+  payload: IGatsbyNode
+}
+
+export interface IAddChildNodeToParentNodeAction {
+  type: `ADD_CHILD_NODE_TO_PARENT_NODE`
+  payload: IGatsbyNode
+}
+
+export interface IDeleteNodeAction {
+  type: `DELETE_NODE`
+  payload: {
+    id: Identifier
+  }
+}
+
+export interface IDeleteNodesAction {
+  type: `DELETE_NODES`
+  payload: Identifier[]
+}