diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarian.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarian.cs
new file mode 100644
index 000000000..763735d51
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarian.cs
@@ -0,0 +1,153 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using FluentValidation.Results;
+using NLog;
+using NzbDrone.Common.Cache;
+using NzbDrone.Common.Extensions;
+using NzbDrone.Core.Configuration;
+using NzbDrone.Core.Indexers;
+
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarian : ApplicationBase<LazyLibrarianSettings>
+    {
+        public override string Name => "LazyLibrarian";
+
+        private readonly ILazyLibrarianV1Proxy _lazyLibrarianV1Proxy;
+        private readonly IConfigFileProvider _configFileProvider;
+
+        public LazyLibrarian(ILazyLibrarianV1Proxy lazyLibrarianV1Proxy, IConfigFileProvider configFileProvider, IAppIndexerMapService appIndexerMapService, Logger logger)
+            : base(appIndexerMapService, logger)
+        {
+            _lazyLibrarianV1Proxy = lazyLibrarianV1Proxy;
+            _configFileProvider = configFileProvider;
+        }
+
+        public override ValidationResult Test()
+        {
+            var failures = new List<ValidationFailure>();
+
+            try
+            {
+                failures.AddIfNotNull(_lazyLibrarianV1Proxy.TestConnection(Settings));
+            }
+            catch (WebException ex)
+            {
+                _logger.Error(ex, "Unable to send test message");
+                failures.AddIfNotNull(new ValidationFailure("BaseUrl", "Unable to complete application test, cannot connect to LazyLibrarian"));
+            }
+
+            return new ValidationResult(failures);
+        }
+
+        public override List<AppIndexerMap> GetIndexerMappings()
+        {
+            var indexers = _lazyLibrarianV1Proxy.GetIndexers(Settings);
+
+            var mappings = new List<AppIndexerMap>();
+
+            foreach (var indexer in indexers)
+            {
+                if (indexer.Apikey == _configFileProvider.ApiKey)
+                {
+                    var match = AppIndexerRegex.Match(indexer.Host);
+
+                    if (match.Groups["indexer"].Success && int.TryParse(match.Groups["indexer"].Value, out var indexerId))
+                    {
+                        //Add parsed mapping if it's mapped to a Indexer in this Prowlarr instance
+                        mappings.Add(new AppIndexerMap { RemoteIndexerName = $"{indexer.Type},{indexer.Name}", IndexerId = indexerId });
+                    }
+                }
+            }
+
+            return mappings;
+        }
+
+        public override void AddIndexer(IndexerDefinition indexer)
+        {
+            if (indexer.Capabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray()).Any())
+            {
+                var lazyLibrarianIndexer = BuildLazyLibrarianIndexer(indexer, indexer.Protocol);
+
+                var remoteIndexer = _lazyLibrarianV1Proxy.AddIndexer(lazyLibrarianIndexer, Settings);
+                _appIndexerMapService.Insert(new AppIndexerMap { AppId = Definition.Id, IndexerId = indexer.Id, RemoteIndexerName = $"{remoteIndexer.Type},{remoteIndexer.Name}" });
+            }
+        }
+
+        public override void RemoveIndexer(int indexerId)
+        {
+            var appMappings = _appIndexerMapService.GetMappingsForApp(Definition.Id);
+
+            var indexerMapping = appMappings.FirstOrDefault(m => m.IndexerId == indexerId);
+
+            if (indexerMapping != null)
+            {
+                //Remove Indexer remotely and then remove the mapping
+                var indexerProps = indexerMapping.RemoteIndexerName.Split(",");
+                _lazyLibrarianV1Proxy.RemoveIndexer(indexerProps[1], (LazyLibrarianProviderType)Enum.Parse(typeof(LazyLibrarianProviderType), indexerProps[0]), Settings);
+                _appIndexerMapService.Delete(indexerMapping.Id);
+            }
+        }
+
+        public override void UpdateIndexer(IndexerDefinition indexer)
+        {
+            _logger.Debug("Updating indexer {0} [{1}]", indexer.Name, indexer.Id);
+
+            var appMappings = _appIndexerMapService.GetMappingsForApp(Definition.Id);
+            var indexerMapping = appMappings.FirstOrDefault(m => m.IndexerId == indexer.Id);
+            var indexerProps = indexerMapping.RemoteIndexerName.Split(",");
+
+            var lazyLibrarianIndexer = BuildLazyLibrarianIndexer(indexer, indexer.Protocol, indexerProps[1]);
+
+            //Use the old remote id to find the indexer on LazyLibrarian incase the update was from a name change in Prowlarr
+            var remoteIndexer = _lazyLibrarianV1Proxy.GetIndexer(indexerProps[1], lazyLibrarianIndexer.Type, Settings);
+
+            if (remoteIndexer != null)
+            {
+                _logger.Debug("Remote indexer found, syncing with current settings");
+
+                if (!lazyLibrarianIndexer.Equals(remoteIndexer))
+                {
+                    _lazyLibrarianV1Proxy.UpdateIndexer(lazyLibrarianIndexer, Settings);
+                    indexerMapping.RemoteIndexerName = $"{lazyLibrarianIndexer.Type},{lazyLibrarianIndexer.Altername}";
+                    _appIndexerMapService.Update(indexerMapping);
+                }
+            }
+            else
+            {
+                _appIndexerMapService.Delete(indexerMapping.Id);
+
+                if (indexer.Capabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray()).Any())
+                {
+                    _logger.Debug("Remote indexer not found, re-adding {0} to LazyLibrarian", indexer.Name);
+                    var newRemoteIndexer = _lazyLibrarianV1Proxy.AddIndexer(lazyLibrarianIndexer, Settings);
+                    _appIndexerMapService.Insert(new AppIndexerMap { AppId = Definition.Id, IndexerId = indexer.Id, RemoteIndexerName = $"{newRemoteIndexer.Type},{newRemoteIndexer.Name}" });
+                }
+                else
+                {
+                    _logger.Debug("Remote indexer not found for {0}, skipping re-add to LazyLibrarian due to indexer capabilities", indexer.Name);
+                }
+            }
+        }
+
+        private LazyLibrarianIndexer BuildLazyLibrarianIndexer(IndexerDefinition indexer, DownloadProtocol protocol, string originalName = null)
+        {
+            var schema = protocol == DownloadProtocol.Usenet ? LazyLibrarianProviderType.Newznab : LazyLibrarianProviderType.Torznab;
+
+            var lazyLibrarianIndexer = new LazyLibrarianIndexer
+            {
+                Name = originalName ?? $"{indexer.Name} (Prowlarr)",
+                Altername = $"{indexer.Name} (Prowlarr)",
+                Host = $"{Settings.ProwlarrUrl.TrimEnd('/')}/{indexer.Id}/api",
+                Apikey = _configFileProvider.ApiKey,
+                Categories = string.Join(",", indexer.Capabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray())),
+                Enabled = indexer.Enable,
+                Type = schema,
+            };
+
+            return lazyLibrarianIndexer;
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianError.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianError.cs
new file mode 100644
index 000000000..65338ae92
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianError.cs
@@ -0,0 +1,8 @@
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarianError
+    {
+        public int Code { get; set; }
+        public string Message { get; set; }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianException.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianException.cs
new file mode 100644
index 000000000..ab0d32749
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianException.cs
@@ -0,0 +1,23 @@
+using System;
+using NzbDrone.Common.Exceptions;
+
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarianException : NzbDroneException
+    {
+        public LazyLibrarianException(string message)
+            : base(message)
+        {
+        }
+
+        public LazyLibrarianException(string message, params object[] args)
+            : base(message, args)
+        {
+        }
+
+        public LazyLibrarianException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianIndexer.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianIndexer.cs
new file mode 100644
index 000000000..ff77f47b7
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianIndexer.cs
@@ -0,0 +1,49 @@
+using System.Collections.Generic;
+
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarianIndexerResponse
+    {
+        public bool Success { get; set; }
+        public LazyLibrarianIndexerData Data { get; set; }
+        public LazyLibrarianError Error { get; set; }
+    }
+
+    public class LazyLibrarianIndexerData
+    {
+        public List<LazyLibrarianIndexer> Torznabs { get; set; }
+        public List<LazyLibrarianIndexer> Newznabs { get; set; }
+    }
+
+    public enum LazyLibrarianProviderType
+    {
+        Newznab,
+        Torznab
+    }
+
+    public class LazyLibrarianIndexer
+    {
+        public string Name { get; set; }
+        public string Host { get; set; }
+        public string Apikey { get; set; }
+        public string Categories { get; set; }
+        public bool Enabled { get; set; }
+        public string Altername { get; set; }
+        public LazyLibrarianProviderType Type { get; set; }
+
+        public bool Equals(LazyLibrarianIndexer other)
+        {
+            if (ReferenceEquals(null, other))
+            {
+                return false;
+            }
+
+            return other.Host == Host &&
+                other.Apikey == Apikey &&
+                other.Name == Name &&
+                other.Categories == Categories &&
+                other.Enabled == Enabled &&
+                other.Altername == Altername;
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianSettings.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianSettings.cs
new file mode 100644
index 000000000..e6c8df3dd
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianSettings.cs
@@ -0,0 +1,58 @@
+using System.Collections.Generic;
+using FluentValidation;
+using NzbDrone.Core.Annotations;
+using NzbDrone.Core.Indexers;
+using NzbDrone.Core.Validation;
+
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarianSettingsValidator : AbstractValidator<LazyLibrarianSettings>
+    {
+        public LazyLibrarianSettingsValidator()
+        {
+            RuleFor(c => c.BaseUrl).IsValidUrl();
+            RuleFor(c => c.ProwlarrUrl).IsValidUrl();
+            RuleFor(c => c.ApiKey).NotEmpty();
+            RuleFor(c => c.SyncCategories).NotEmpty();
+        }
+    }
+
+    public class LazyLibrarianSettings : IApplicationSettings
+    {
+        private static readonly LazyLibrarianSettingsValidator Validator = new LazyLibrarianSettingsValidator();
+
+        public LazyLibrarianSettings()
+        {
+            ProwlarrUrl = "http://localhost:9696";
+            BaseUrl = "http://localhost:5299";
+            SyncCategories = new[]
+            {
+                NewznabStandardCategory.AudioAudiobook.Id,
+                NewznabStandardCategory.Books.Id,
+                NewznabStandardCategory.BooksComics.Id,
+                NewznabStandardCategory.BooksEBook.Id,
+                NewznabStandardCategory.BooksForeign.Id,
+                NewznabStandardCategory.BooksMags.Id,
+                NewznabStandardCategory.BooksOther.Id,
+                NewznabStandardCategory.BooksTechnical.Id,
+            };
+        }
+
+        [FieldDefinition(0, Label = "Prowlarr Server", HelpText = "Prowlarr server URL as LazyLibrarian sees it, including http(s)://, port, and urlbase if needed")]
+        public string ProwlarrUrl { get; set; }
+
+        [FieldDefinition(1, Label = "LazyLibrarian Server", HelpText = "URL used to connect to LazyLibrarian server, including http(s)://, port, and urlbase if required")]
+        public string BaseUrl { get; set; }
+
+        [FieldDefinition(2, Label = "ApiKey", Privacy = PrivacyLevel.ApiKey, HelpText = "The ApiKey generated by LazyLibrarian in Settings/Web Interface")]
+        public string ApiKey { get; set; }
+
+        [FieldDefinition(3, Label = "Sync Categories", Type = FieldType.Select, SelectOptions = typeof(NewznabCategoryFieldConverter), Advanced = true, HelpText = "Only Indexers that support these categories will be synced")]
+        public IEnumerable<int> SyncCategories { get; set; }
+
+        public NzbDroneValidationResult Validate()
+        {
+            return new NzbDroneValidationResult(Validator.Validate(this));
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianStatus.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianStatus.cs
new file mode 100644
index 000000000..869bd50dd
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianStatus.cs
@@ -0,0 +1,8 @@
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public class LazyLibrarianStatus
+    {
+        public bool Success { get; set; }
+        public LazyLibrarianError Error { get; set; }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianV1Proxy.cs b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianV1Proxy.cs
new file mode 100644
index 000000000..13cc2aa85
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/LazyLibrarian/LazyLibrarianV1Proxy.cs
@@ -0,0 +1,187 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using FluentValidation.Results;
+using Newtonsoft.Json;
+using NLog;
+using NzbDrone.Common.Http;
+
+namespace NzbDrone.Core.Applications.LazyLibrarian
+{
+    public interface ILazyLibrarianV1Proxy
+    {
+        LazyLibrarianIndexer AddIndexer(LazyLibrarianIndexer indexer, LazyLibrarianSettings settings);
+        List<LazyLibrarianIndexer> GetIndexers(LazyLibrarianSettings settings);
+        LazyLibrarianIndexer GetIndexer(string indexerName, LazyLibrarianProviderType indexerType, LazyLibrarianSettings settings);
+        void RemoveIndexer(string indexerName, LazyLibrarianProviderType indexerType, LazyLibrarianSettings settings);
+        LazyLibrarianIndexer UpdateIndexer(LazyLibrarianIndexer indexer, LazyLibrarianSettings settings);
+        ValidationFailure TestConnection(LazyLibrarianSettings settings);
+    }
+
+    public class LazyLibrarianV1Proxy : ILazyLibrarianV1Proxy
+    {
+        private readonly IHttpClient _httpClient;
+        private readonly Logger _logger;
+
+        public LazyLibrarianV1Proxy(IHttpClient httpClient, Logger logger)
+        {
+            _httpClient = httpClient;
+            _logger = logger;
+        }
+
+        public LazyLibrarianStatus GetStatus(LazyLibrarianSettings settings)
+        {
+            var request = BuildRequest(settings, "/api", "getVersion", HttpMethod.GET);
+            return Execute<LazyLibrarianStatus>(request);
+        }
+
+        public List<LazyLibrarianIndexer> GetIndexers(LazyLibrarianSettings settings)
+        {
+            var request = BuildRequest(settings, "/api", "listProviders", HttpMethod.GET);
+
+            var response = Execute<LazyLibrarianIndexerResponse>(request);
+
+            if (!response.Success)
+            {
+                throw new LazyLibrarianException(string.Format("LazyLibrarian Error - Code {0}: {1}", response.Error.Code, response.Error.Message));
+            }
+
+            var indexers = new List<LazyLibrarianIndexer>();
+
+            var torIndexers = response.Data.Torznabs;
+            torIndexers.ForEach(i => i.Type = LazyLibrarianProviderType.Torznab);
+
+            var nzbIndexers = response.Data.Newznabs;
+            nzbIndexers.ForEach(i => i.Type = LazyLibrarianProviderType.Newznab);
+
+            indexers.AddRange(torIndexers);
+            indexers.AddRange(nzbIndexers);
+            indexers.ForEach(i => i.Altername = i.Name);
+
+            return indexers;
+        }
+
+        public LazyLibrarianIndexer GetIndexer(string indexerName, LazyLibrarianProviderType indexerType, LazyLibrarianSettings settings)
+        {
+            var indexers = GetIndexers(settings);
+
+            return indexers.SingleOrDefault(i => i.Name == indexerName && i.Type == indexerType);
+        }
+
+        public void RemoveIndexer(string indexerName, LazyLibrarianProviderType indexerType, LazyLibrarianSettings settings)
+        {
+            var parameters = new Dictionary<string, string>
+            {
+                { "name", indexerName },
+                { "providertype", indexerType.ToString().ToLower() }
+            };
+
+            var request = BuildRequest(settings, "/api", "delProvider", HttpMethod.GET, parameters);
+            CheckForError(Execute<LazyLibrarianStatus>(request));
+        }
+
+        public LazyLibrarianIndexer AddIndexer(LazyLibrarianIndexer indexer, LazyLibrarianSettings settings)
+        {
+            var parameters = new Dictionary<string, string>
+            {
+                { "name", indexer.Name },
+                { "providertype", indexer.Type.ToString().ToLower() },
+                { "host", indexer.Host },
+                { "prov_apikey", indexer.Apikey },
+                { "enabled", indexer.Enabled.ToString().ToLower() },
+                { "categories", indexer.Categories }
+            };
+
+            var request = BuildRequest(settings, "/api", "addProvider", HttpMethod.GET, parameters);
+            CheckForError(Execute<LazyLibrarianStatus>(request));
+            return indexer;
+        }
+
+        public LazyLibrarianIndexer UpdateIndexer(LazyLibrarianIndexer indexer, LazyLibrarianSettings settings)
+        {
+            var parameters = new Dictionary<string, string>
+            {
+                { "name", indexer.Name },
+                { "providertype", indexer.Type.ToString().ToLower() },
+                { "host", indexer.Host },
+                { "prov_apikey", indexer.Apikey },
+                { "enabled", indexer.Enabled.ToString().ToLower() },
+                { "categories", indexer.Categories },
+                { "altername", indexer.Altername }
+            };
+
+            var request = BuildRequest(settings, "/api", "changeProvider", HttpMethod.GET, parameters);
+            CheckForError(Execute<LazyLibrarianStatus>(request));
+            return indexer;
+        }
+
+        private void CheckForError(LazyLibrarianStatus response)
+        {
+            if (!response.Success)
+            {
+                throw new LazyLibrarianException(string.Format("LazyLibrarian Error - Code {0}: {1}", response.Error.Code, response.Error.Message));
+            }
+        }
+
+        public ValidationFailure TestConnection(LazyLibrarianSettings settings)
+        {
+            try
+            {
+                var status = GetStatus(settings);
+
+                if (!status.Success)
+                {
+                    return new ValidationFailure("ApiKey", status.Error.Message);
+                }
+            }
+            catch (HttpException ex)
+            {
+                _logger.Error(ex, "Unable to send test message");
+                return new ValidationFailure("BaseUrl", "Unable to complete application test");
+            }
+            catch (Exception ex)
+            {
+                _logger.Error(ex, "Unable to send test message");
+                return new ValidationFailure("", "Unable to send test message");
+            }
+
+            return null;
+        }
+
+        private HttpRequest BuildRequest(LazyLibrarianSettings settings, string resource, string command, HttpMethod method, Dictionary<string, string> parameters = null)
+        {
+            var baseUrl = settings.BaseUrl.TrimEnd('/');
+
+            var requestBuilder = new HttpRequestBuilder(baseUrl).Resource(resource)
+                .AddQueryParam("cmd", command)
+                .AddQueryParam("apikey", settings.ApiKey);
+
+            if (parameters != null)
+            {
+                foreach (var param in parameters)
+                {
+                    requestBuilder.AddQueryParam(param.Key, param.Value);
+                }
+            }
+
+            var request = requestBuilder.Build();
+
+            request.Headers.ContentType = "application/json";
+
+            request.Method = method;
+            request.AllowAutoRedirect = true;
+
+            return request;
+        }
+
+        private TResource Execute<TResource>(HttpRequest request)
+             where TResource : new()
+        {
+            var response = _httpClient.Execute(request);
+
+            var results = JsonConvert.DeserializeObject<TResource>(response.Content);
+
+            return results;
+        }
+    }
+}