diff --git a/app/Api/V1/Controllers/Models/TransactionLink/DestroyController.php b/app/Api/V1/Controllers/Models/TransactionLink/DestroyController.php
new file mode 100644
index 0000000000..4c8f56315d
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLink/DestroyController.php
@@ -0,0 +1,56 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLink;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+use FireflyIII\Models\TransactionJournalLink;
+use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
+use FireflyIII\User;
+use Illuminate\Http\JsonResponse;
+
+class DestroyController extends Controller
+{
+
+    private LinkTypeRepositoryInterface $repository;
+
+
+    /**
+     * TransactionLinkController constructor.
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                /** @var User $user */
+                $user = auth()->user();
+
+                $this->repository = app(LinkTypeRepositoryInterface::class);
+
+                $this->repository->setUser($user);
+
+                return $next($request);
+            }
+        );
+    }
+
+    /**
+     * Delete the resource.
+     *
+     * @param TransactionJournalLink $link
+     *
+     * @return JsonResponse
+     * @codeCoverageIgnore
+     */
+    public function destroy(TransactionJournalLink $link): JsonResponse
+    {
+        $this->repository->destroyLink($link);
+
+        return response()->json([], 204);
+    }
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLink/ShowController.php b/app/Api/V1/Controllers/Models/TransactionLink/ShowController.php
new file mode 100644
index 0000000000..925127adbb
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLink/ShowController.php
@@ -0,0 +1,108 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLink;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+use FireflyIII\Models\TransactionJournalLink;
+use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
+use FireflyIII\Transformers\TransactionLinkTransformer;
+use FireflyIII\User;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Pagination\LengthAwarePaginator;
+use League\Fractal\Pagination\IlluminatePaginatorAdapter;
+use League\Fractal\Resource\Collection as FractalCollection;
+use League\Fractal\Resource\Item;
+
+class ShowController extends Controller
+{
+    private LinkTypeRepositoryInterface $repository;
+
+    /**
+     * TransactionLinkController constructor.
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                /** @var User $user */
+                $user = auth()->user();
+
+                $this->repository = app(LinkTypeRepositoryInterface::class);
+
+                $this->repository->setUser($user);
+
+                return $next($request);
+            }
+        );
+    }
+
+    /**
+     * List all of the transaction links there are.
+     *
+     * @param Request $request
+     *
+     * @return JsonResponse
+     * @codeCoverageIgnore
+     */
+    public function index(Request $request): JsonResponse
+    {
+        // create some objects:
+        $manager = $this->getManager();
+        // read type from URI
+        $name = $request->get('name');
+
+        // types to get, page size:
+        $pageSize = (int)app('preferences')->getForUser(auth()->user(), 'listPageSize', 50)->data;
+        $linkType = $this->repository->findByName($name);
+
+        // get list of transaction links. Count it and split it.
+        $collection   = $this->repository->getJournalLinks($linkType);
+        $count        = $collection->count();
+        $journalLinks = $collection->slice(($this->parameters->get('page') - 1) * $pageSize, $pageSize);
+
+        // make paginator:
+        $paginator = new LengthAwarePaginator($journalLinks, $count, $pageSize, $this->parameters->get('page'));
+        $paginator->setPath(route('api.v1.transaction_links.index') . $this->buildParams());
+
+        /** @var TransactionLinkTransformer $transformer */
+        $transformer = app(TransactionLinkTransformer::class);
+        $transformer->setParameters($this->parameters);
+
+        $resource = new FractalCollection($journalLinks, $transformer, 'transaction_links');
+        $resource->setPaginator(new IlluminatePaginatorAdapter($paginator));
+
+        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
+
+    }
+
+
+    /**
+     * List single resource.
+     *
+     * @param TransactionJournalLink $journalLink
+     *
+     * @return JsonResponse
+     * @codeCoverageIgnore
+     */
+    public function show(TransactionJournalLink $journalLink): JsonResponse
+    {
+        $manager = $this->getManager();
+
+        /** @var TransactionLinkTransformer $transformer */
+        $transformer = app(TransactionLinkTransformer::class);
+        $transformer->setParameters($this->parameters);
+
+        $resource = new Item($journalLink, $transformer, 'transaction_links');
+
+        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
+
+    }
+
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLink/StoreController.php b/app/Api/V1/Controllers/Models/TransactionLink/StoreController.php
new file mode 100644
index 0000000000..856dd39e34
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLink/StoreController.php
@@ -0,0 +1,79 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLink;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+use FireflyIII\Api\V1\Requests\Models\TransactionLink\StoreRequest;
+use FireflyIII\Exceptions\FireflyException;
+use FireflyIII\Repositories\Journal\JournalRepositoryInterface;
+use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
+use FireflyIII\Support\Http\Api\TransactionFilter;
+use FireflyIII\Transformers\TransactionLinkTransformer;
+use FireflyIII\User;
+use Illuminate\Http\JsonResponse;
+use League\Fractal\Resource\Item;
+
+class StoreController extends Controller
+{
+    use TransactionFilter;
+    private JournalRepositoryInterface $journalRepository;
+    private LinkTypeRepositoryInterface $repository;
+
+
+    /**
+     * TransactionLinkController constructor.
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                /** @var User $user */
+                $user = auth()->user();
+
+                $this->repository        = app(LinkTypeRepositoryInterface::class);
+                $this->journalRepository = app(JournalRepositoryInterface::class);
+
+                $this->repository->setUser($user);
+                $this->journalRepository->setUser($user);
+
+                return $next($request);
+            }
+        );
+    }
+
+
+    /**
+     * Store new object.
+     *
+     * @param StoreRequest $request
+     *
+     * @return JsonResponse
+     * @throws FireflyException
+     */
+    public function store(StoreRequest $request): JsonResponse
+    {
+        $manager = $this->getManager();
+        $data    = $request->getAll();
+        $inward  = $this->journalRepository->findNull($data['inward_id'] ?? 0);
+        $outward = $this->journalRepository->findNull($data['outward_id'] ?? 0);
+        if (null === $inward || null === $outward) {
+            throw new FireflyException('200024: Source or destination does not exist.');
+        }
+        $data['direction'] = 'inward';
+
+        $journalLink = $this->repository->storeLink($data, $inward, $outward);
+
+        /** @var TransactionLinkTransformer $transformer */
+        $transformer = app(TransactionLinkTransformer::class);
+        $transformer->setParameters($this->parameters);
+
+        $resource = new Item($journalLink, $transformer, 'transaction_links');
+
+        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
+    }
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLink/UpdateController.php b/app/Api/V1/Controllers/Models/TransactionLink/UpdateController.php
new file mode 100644
index 0000000000..85aa3f4ee4
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLink/UpdateController.php
@@ -0,0 +1,78 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLink;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+use FireflyIII\Api\V1\Requests\Models\TransactionLink\UpdateRequest;
+use FireflyIII\Exceptions\FireflyException;
+use FireflyIII\Models\TransactionJournalLink;
+use FireflyIII\Repositories\Journal\JournalRepositoryInterface;
+use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
+use FireflyIII\Transformers\TransactionLinkTransformer;
+use FireflyIII\User;
+use Illuminate\Http\JsonResponse;
+use League\Fractal\Resource\Item;
+
+class UpdateController extends Controller
+{
+    private JournalRepositoryInterface  $journalRepository;
+    private LinkTypeRepositoryInterface $repository;
+
+
+    /**
+     * TransactionLinkController constructor.
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                /** @var User $user */
+                $user = auth()->user();
+
+                $this->repository        = app(LinkTypeRepositoryInterface::class);
+                $this->journalRepository = app(JournalRepositoryInterface::class);
+
+                $this->repository->setUser($user);
+                $this->journalRepository->setUser($user);
+
+                return $next($request);
+            }
+        );
+    }
+
+    /**
+     * Update object.
+     *
+     * @param UpdateRequest          $request
+     * @param TransactionJournalLink $journalLink
+     *
+     * @return JsonResponse
+     * @throws FireflyException
+     */
+    public function update(UpdateRequest $request, TransactionJournalLink $journalLink): JsonResponse
+    {
+        $manager         = $this->getManager();
+        $data            = $request->getAll();
+        $data['inward']  = $this->journalRepository->findNull($data['inward_id'] ?? 0);
+        $data['outward'] = $this->journalRepository->findNull($data['outward_id'] ?? 0);
+        if (null === $data['inward'] || null === $data['outward']) {
+            throw new FireflyException('200024: Source or destination does not exist.');
+        }
+        $data['direction'] = 'inward';
+        $journalLink       = $this->repository->updateLink($journalLink, $data);
+
+        /** @var TransactionLinkTransformer $transformer */
+        $transformer = app(TransactionLinkTransformer::class);
+        $transformer->setParameters($this->parameters);
+
+        $resource = new Item($journalLink, $transformer, 'transaction_links');
+
+        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
+
+    }
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLinkType/DestroyController.php b/app/Api/V1/Controllers/Models/TransactionLinkType/DestroyController.php
new file mode 100644
index 0000000000..c6f89b4044
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLinkType/DestroyController.php
@@ -0,0 +1,15 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLinkType;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+
+/**
+ * Class DestroyController
+ */
+class DestroyController extends Controller
+{
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLinkType/ListController.php b/app/Api/V1/Controllers/Models/TransactionLinkType/ListController.php
new file mode 100644
index 0000000000..687466ceeb
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLinkType/ListController.php
@@ -0,0 +1,15 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLinkType;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+
+/**
+ * Class ListController
+ */
+class ListController extends Controller
+{
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLinkType/ShowController.php b/app/Api/V1/Controllers/Models/TransactionLinkType/ShowController.php
new file mode 100644
index 0000000000..a0291abb47
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLinkType/ShowController.php
@@ -0,0 +1,15 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLinkType;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+
+/**
+ * Class ShowController
+ */
+class ShowController extends Controller
+{
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLinkType/StoreController.php b/app/Api/V1/Controllers/Models/TransactionLinkType/StoreController.php
new file mode 100644
index 0000000000..fccedd32a1
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLinkType/StoreController.php
@@ -0,0 +1,15 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLinkType;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+
+/**
+ * Class StoreController
+ */
+class StoreController extends Controller
+{
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/Models/TransactionLinkType/UpdateController.php b/app/Api/V1/Controllers/Models/TransactionLinkType/UpdateController.php
new file mode 100644
index 0000000000..5a1610064d
--- /dev/null
+++ b/app/Api/V1/Controllers/Models/TransactionLinkType/UpdateController.php
@@ -0,0 +1,15 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionLinkType;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+
+/**
+ * Class UpdateController
+ */
+class UpdateController extends Controller
+{
+
+}
\ No newline at end of file
diff --git a/app/Api/V1/Controllers/todo/TransactionLinkController.php b/app/Api/V1/Controllers/todo/TransactionLinkController.php
index d4b3ade13d..92b2d50d3c 100644
--- a/app/Api/V1/Controllers/todo/TransactionLinkController.php
+++ b/app/Api/V1/Controllers/todo/TransactionLinkController.php
@@ -43,173 +43,6 @@ use League\Fractal\Resource\Item;
  */
 class TransactionLinkController extends Controller
 {
-    use TransactionFilter;
-
-    /** @var JournalRepositoryInterface The journal repository */
-    private $journalRepository;
-
-    /** @var LinkTypeRepositoryInterface The link type repository */
-    private $repository;
 
 
-    /**
-     * TransactionLinkController constructor.
-     *
-     * @codeCoverageIgnore
-     */
-    public function __construct()
-    {
-        parent::__construct();
-        $this->middleware(
-            function ($request, $next) {
-                /** @var User $user */
-                $user = auth()->user();
-
-                $this->repository        = app(LinkTypeRepositoryInterface::class);
-                $this->journalRepository = app(JournalRepositoryInterface::class);
-
-                $this->repository->setUser($user);
-                $this->journalRepository->setUser($user);
-
-                return $next($request);
-            }
-        );
-    }
-
-    /**
-     * Delete the resource.
-     *
-     * @param TransactionJournalLink $link
-     *
-     * @return JsonResponse
-     * @codeCoverageIgnore
-     */
-    public function delete(TransactionJournalLink $link): JsonResponse
-    {
-        $this->repository->destroyLink($link);
-
-        return response()->json([], 204);
-    }
-
-    /**
-     * List all of them.
-     *
-     * @param Request $request
-     *
-     * @return JsonResponse
-     * @codeCoverageIgnore
-     */
-    public function index(Request $request): JsonResponse
-    {
-        // create some objects:
-        $manager = $this->getManager();
-        // read type from URI
-        $name = $request->get('name');
-
-        // types to get, page size:
-        $pageSize = (int) app('preferences')->getForUser(auth()->user(), 'listPageSize', 50)->data;
-        $linkType = $this->repository->findByName($name);
-
-        // get list of transaction links. Count it and split it.
-        $collection   = $this->repository->getJournalLinks($linkType);
-        $count        = $collection->count();
-        $journalLinks = $collection->slice(($this->parameters->get('page') - 1) * $pageSize, $pageSize);
-
-        // make paginator:
-        $paginator = new LengthAwarePaginator($journalLinks, $count, $pageSize, $this->parameters->get('page'));
-        $paginator->setPath(route('api.v1.transaction_links.index') . $this->buildParams());
-
-        /** @var TransactionLinkTransformer $transformer */
-        $transformer = app(TransactionLinkTransformer::class);
-        $transformer->setParameters($this->parameters);
-
-        $resource = new FractalCollection($journalLinks, $transformer, 'transaction_links');
-        $resource->setPaginator(new IlluminatePaginatorAdapter($paginator));
-
-        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
-
-    }
-
-    /**
-     * List single resource.
-     *
-     * @param TransactionJournalLink $journalLink
-     *
-     * @return JsonResponse
-     * @codeCoverageIgnore
-     */
-    public function show(TransactionJournalLink $journalLink): JsonResponse
-    {
-        $manager = $this->getManager();
-
-        /** @var TransactionLinkTransformer $transformer */
-        $transformer = app(TransactionLinkTransformer::class);
-        $transformer->setParameters($this->parameters);
-
-        $resource = new Item($journalLink, $transformer, 'transaction_links');
-
-        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
-
-    }
-
-    /**
-     * Store new object.
-     *
-     * @param TransactionLinkRequest $request
-     *
-     * @return JsonResponse
-     * @throws FireflyException
-     */
-    public function store(TransactionLinkRequest $request): JsonResponse
-    {
-        $manager = $this->getManager();
-        $data    = $request->getAll();
-        $inward  = $this->journalRepository->findNull($data['inward_id'] ?? 0);
-        $outward = $this->journalRepository->findNull($data['outward_id'] ?? 0);
-        if (null === $inward || null === $outward) {
-            throw new FireflyException('200024: Source or destination does not exist.');
-        }
-        $data['direction'] = 'inward';
-
-        $journalLink = $this->repository->storeLink($data, $inward, $outward);
-
-        /** @var TransactionLinkTransformer $transformer */
-        $transformer = app(TransactionLinkTransformer::class);
-        $transformer->setParameters($this->parameters);
-
-        $resource = new Item($journalLink, $transformer, 'transaction_links');
-
-        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
-    }
-
-    /**
-     * Update object.
-     *
-     * @param TransactionLinkRequest $request
-     * @param TransactionJournalLink $journalLink
-     *
-     * @return JsonResponse
-     * @throws FireflyException
-     */
-    public function update(TransactionLinkRequest $request, TransactionJournalLink $journalLink): JsonResponse
-    {
-        $manager         = $this->getManager();
-        $data            = $request->getAll();
-        $data['inward']  = $this->journalRepository->findNull($data['inward_id'] ?? 0);
-        $data['outward'] = $this->journalRepository->findNull($data['outward_id'] ?? 0);
-        if (null === $data['inward'] || null === $data['outward']) {
-            throw new FireflyException('200024: Source or destination does not exist.');
-        }
-        $data['direction'] = 'inward';
-        $journalLink       = $this->repository->updateLink($journalLink, $data);
-
-        /** @var TransactionLinkTransformer $transformer */
-        $transformer = app(TransactionLinkTransformer::class);
-        $transformer->setParameters($this->parameters);
-
-        $resource = new Item($journalLink, $transformer, 'transaction_links');
-
-        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', self::CONTENT_TYPE);
-
-    }
 }
diff --git a/app/Api/V1/Requests/todo/TransactionLinkRequest.php b/app/Api/V1/Requests/Models/TransactionLink/StoreRequest.php
similarity index 97%
rename from app/Api/V1/Requests/todo/TransactionLinkRequest.php
rename to app/Api/V1/Requests/Models/TransactionLink/StoreRequest.php
index 00c94d7306..1b8540728f 100644
--- a/app/Api/V1/Requests/todo/TransactionLinkRequest.php
+++ b/app/Api/V1/Requests/Models/TransactionLink/StoreRequest.php
@@ -21,7 +21,7 @@
 
 declare(strict_types=1);
 
-namespace FireflyIII\Api\V1\Requests;
+namespace FireflyIII\Api\V1\Requests\Models\TransactionLink;
 
 use FireflyIII\Repositories\Journal\JournalRepositoryInterface;
 use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
@@ -32,14 +32,12 @@ use Illuminate\Foundation\Http\FormRequest;
 use Illuminate\Validation\Validator;
 
 /**
- * Class TransactionLinkRequest
+ * Class StoreRequest
  */
-class TransactionLinkRequest extends FormRequest
+class StoreRequest extends FormRequest
 {
     use ConvertsDataTypes, ChecksLogin;
 
-
-
     /**
      * Get all data from the request.
      *
diff --git a/app/Api/V1/Requests/Models/TransactionLink/UpdateRequest.php b/app/Api/V1/Requests/Models/TransactionLink/UpdateRequest.php
new file mode 100644
index 0000000000..041d498aa6
--- /dev/null
+++ b/app/Api/V1/Requests/Models/TransactionLink/UpdateRequest.php
@@ -0,0 +1,130 @@
+<?php
+/**
+ * TransactionLinkRequest.php
+ * Copyright (c) 2019 james@firefly-iii.org
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Api\V1\Requests\Models\TransactionLink;
+
+use FireflyIII\Repositories\Journal\JournalRepositoryInterface;
+use FireflyIII\Repositories\LinkType\LinkTypeRepositoryInterface;
+use FireflyIII\Support\Request\ChecksLogin;
+use FireflyIII\Support\Request\ConvertsDataTypes;
+use FireflyIII\User;
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Validator;
+
+/**
+ * Class UpdateRequest
+ */
+class UpdateRequest extends FormRequest
+{
+    use ConvertsDataTypes, ChecksLogin;
+
+    /**
+     * Get all data from the request.
+     *
+     * @return array
+     */
+    public function getAll(): array
+    {
+        return [
+            'link_type_id'   => $this->integer('link_type_id'),
+            'link_type_name' => $this->string('link_type_name'),
+            'inward_id'      => $this->integer('inward_id'),
+            'outward_id'     => $this->integer('outward_id'),
+            'notes'          => $this->nlString('notes'),
+        ];
+    }
+
+    /**
+     * The rules that the incoming request must be matched against.
+     *
+     * @return array
+     */
+    public function rules(): array
+    {
+        return [
+            'link_type_id'   => 'exists:link_types,id',
+            'link_type_name' => 'exists:link_types,name',
+            'inward_id'      => 'belongsToUser:transaction_journals,id|different:outward_id',
+            'outward_id'     => 'belongsToUser:transaction_journals,id|different:inward_id',
+            'notes'          => 'between:0,65000',
+        ];
+    }
+
+    /**
+     * Configure the validator instance.
+     *
+     * @param Validator $validator
+     *
+     * @return void
+     */
+    public function withValidator(Validator $validator): void
+    {
+        $validator->after(
+            function (Validator $validator) {
+                $this->validateExistingLink($validator);
+            }
+        );
+    }
+
+    /**
+     * @param Validator $validator
+     */
+    private function validateExistingLink(Validator $validator): void
+    {
+        /** @var User $user */
+        $user = auth()->user();
+        /** @var LinkTypeRepositoryInterface $repository */
+        $repository = app(LinkTypeRepositoryInterface::class);
+        $repository->setUser($user);
+
+        /** @var JournalRepositoryInterface $journalRepos */
+        $journalRepos = app(JournalRepositoryInterface::class);
+        $journalRepos->setUser($user);
+
+        $data      = $validator->getData();
+        $inwardId  = (int) ($data['inward_id'] ?? 0);
+        $outwardId = (int) ($data['outward_id'] ?? 0);
+        $inward    = $journalRepos->findNull($inwardId);
+        $outward   = $journalRepos->findNull($outwardId);
+
+        if (null === $inward) {
+            $validator->errors()->add('inward_id', 'Invalid inward ID.');
+
+            return;
+        }
+        if (null === $outward) {
+            $validator->errors()->add('outward_id', 'Invalid outward ID.');
+
+            return;
+        }
+
+        if ($repository->findLink($inward, $outward)) {
+            // only if not updating:
+            $link = $this->route()->parameter('journalLink');
+            if (null === $link) {
+                $validator->errors()->add('outward_id', 'Already have a link between inward and outward.');
+                $validator->errors()->add('inward_id', 'Already have a link between inward and outward.');
+            }
+        }
+    }
+}
diff --git a/app/Repositories/LinkType/LinkTypeRepository.php b/app/Repositories/LinkType/LinkTypeRepository.php
index 99be363dce..d1f3276ad8 100644
--- a/app/Repositories/LinkType/LinkTypeRepository.php
+++ b/app/Repositories/LinkType/LinkTypeRepository.php
@@ -328,9 +328,9 @@ class LinkTypeRepository implements LinkTypeRepositoryInterface
      */
     public function updateLink(TransactionJournalLink $journalLink, array $data): TransactionJournalLink
     {
-        $journalLink->source_id      = $data['inward']->id;
-        $journalLink->destination_id = $data['outward']->id;
-        $journalLink->link_type_id   = $data['link_type_id'];
+        $journalLink->source_id      = $data['inward'] ? $data['inward']->id : $journalLink->source_id;
+        $journalLink->destination_id = $data['outward'] ? $data['outward']->id : $journalLink->destination_id;
+        $journalLink->link_type_id   = $data['link_type_id'] ? $data['link_type_id'] : $journalLink->link_type_id;
         $journalLink->save();
         $this->setNoteText($journalLink, $data['notes']);
 
diff --git a/routes/api.php b/routes/api.php
index 75bb44924e..f7ca44d212 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -431,7 +431,19 @@ Route::group(
     }
 );
 
+// Transaction Links API routes:
+Route::group(
+    ['namespace' => 'FireflyIII\Api\V1\Controllers\Models\TransactionLink', 'prefix' => 'transaction_links',
+     'as'        => 'api.v1.transaction_links.',],
+    static function () {
 
+        Route::get('', ['uses' => 'ShowController@index', 'as' => 'index']);
+        Route::post('', ['uses' => 'StoreController@store', 'as' => 'store']);
+        Route::get('{journalLink}', ['uses' => 'ShowController@show', 'as' => 'show']);
+        Route::put('{journalLink}', ['uses' => 'UpdateController@update', 'as' => 'update']);
+        Route::delete('{journalLink}', ['uses' => 'DestroyController@destroy', 'as' => 'delete']);
+    }
+);
 
 
 
@@ -565,21 +577,7 @@ Route::group(
 //        Route::get('{linkType}/transactions', ['uses' => 'LinkTypeController@transactions', 'as' => 'transactions']);
 //    }
 //);
-//
-//// TODO VERIFY API DOCS
-//Route::group(
-//    ['namespace' => 'FireflyIII\Api\V1\Controllers', 'prefix' => 'transaction_links',
-//     'as'        => 'api.v1.transaction_links.',],
-//    static function () {
-//
-//        // Transaction Links API routes:
-//        Route::get('', ['uses' => 'TransactionLinkController@index', 'as' => 'index']);
-//        Route::post('', ['uses' => 'TransactionLinkController@store', 'as' => 'store']);
-//        Route::get('{journalLink}', ['uses' => 'TransactionLinkController@show', 'as' => 'show']);
-//        Route::put('{journalLink}', ['uses' => 'TransactionLinkController@update', 'as' => 'update']);
-//        Route::delete('{journalLink}', ['uses' => 'TransactionLinkController@delete', 'as' => 'delete']);
-//    }
-//);
+
 
 //
 //