diff --git a/src/NzbDrone.Core/Applications/Qui/Qui.cs b/src/NzbDrone.Core/Applications/Qui/Qui.cs
new file mode 100644
index 000000000..dcdc7f852
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/Qui/Qui.cs
@@ -0,0 +1,216 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using FluentValidation.Results;
+using NLog;
+using NzbDrone.Common.Extensions;
+using NzbDrone.Core.Configuration;
+using NzbDrone.Core.Indexers;
+
+namespace NzbDrone.Core.Applications.Qui
+{
+    public class Qui : ApplicationBase<QuiSettings>
+    {
+        public override string Name => "qui";
+
+        private readonly IQuiProxy _quiProxy;
+        private readonly IConfigFileProvider _configFileProvider;
+
+        public Qui(IQuiProxy quiProxy, IConfigFileProvider configFileProvider, IAppIndexerMapService appIndexerMapService, IIndexerFactory indexerFactory, Logger logger)
+            : base(appIndexerMapService, indexerFactory, logger)
+        {
+            _quiProxy = quiProxy;
+            _configFileProvider = configFileProvider;
+        }
+
+        public override ValidationResult Test()
+        {
+            var failures = new List<ValidationFailure>();
+
+            failures.AddIfNotNull(_quiProxy.TestConnection(Settings));
+
+            return new ValidationResult(failures);
+        }
+
+        public override List<AppIndexerMap> GetIndexerMappings()
+        {
+            var indexers = _quiProxy.GetIndexers(Settings);
+
+            var mappings = new List<AppIndexerMap>();
+
+            foreach (var indexer in indexers)
+            {
+                var baseUrl = Settings.ProwlarrUrl.TrimEnd('/');
+
+                if (indexer.Backend == "prowlarr" &&
+                    (indexer.BaseUrl?.TrimEnd('/').Equals(baseUrl, StringComparison.OrdinalIgnoreCase) == true ||
+                     indexer.BaseUrl?.StartsWith(baseUrl + "/", StringComparison.OrdinalIgnoreCase) == true) &&
+                    int.TryParse(indexer.IndexerId, out var indexerId))
+                {
+                    mappings.Add(new AppIndexerMap { IndexerId = indexerId, RemoteIndexerId = indexer.Id });
+                }
+            }
+
+            return mappings;
+        }
+
+        public override void AddIndexer(IndexerDefinition indexer)
+        {
+            if (indexer.Protocol != DownloadProtocol.Torrent)
+            {
+                return;
+            }
+
+            var indexerCapabilities = GetIndexerCapabilities(indexer);
+
+            if (indexerCapabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray()).Empty())
+            {
+                _logger.Trace("Skipping add for indexer {0} [{1}] due to no app Sync Categories supported by the indexer", indexer.Name, indexer.Id);
+
+                return;
+            }
+
+            _logger.Trace("Adding indexer {0} [{1}]", indexer.Name, indexer.Id);
+
+            var quiIndexer = BuildQuiIndexer(indexer, indexerCapabilities);
+
+            var remoteIndexer = _quiProxy.AddIndexer(quiIndexer, Settings);
+
+            if (remoteIndexer == null)
+            {
+                _logger.Debug("Failed to add {0} [{1}]", indexer.Name, indexer.Id);
+
+                return;
+            }
+
+            _appIndexerMapService.Insert(new AppIndexerMap { AppId = Definition.Id, IndexerId = indexer.Id, RemoteIndexerId = remoteIndexer.Id });
+        }
+
+        public override void RemoveIndexer(int indexerId)
+        {
+            var appMappings = _appIndexerMapService.GetMappingsForApp(Definition.Id);
+
+            var indexerMapping = appMappings.FirstOrDefault(m => m.IndexerId == indexerId);
+
+            if (indexerMapping != null)
+            {
+                _quiProxy.RemoveIndexer(indexerMapping.RemoteIndexerId, Settings);
+                _appIndexerMapService.Delete(indexerMapping.Id);
+            }
+        }
+
+        public override void UpdateIndexer(IndexerDefinition indexer, bool forceSync = false)
+        {
+            _logger.Debug("Updating indexer {0} [{1}]", indexer.Name, indexer.Id);
+
+            if (indexer.Protocol != DownloadProtocol.Torrent)
+            {
+                return;
+            }
+
+            var indexerCapabilities = GetIndexerCapabilities(indexer);
+            var appMappings = _appIndexerMapService.GetMappingsForApp(Definition.Id);
+            var indexerMapping = appMappings.FirstOrDefault(m => m.IndexerId == indexer.Id);
+
+            var quiIndexer = BuildQuiIndexer(indexer, indexerCapabilities, indexerMapping?.RemoteIndexerId ?? 0);
+
+            var remoteIndexer = indexerMapping?.RemoteIndexerId > 0
+                ? _quiProxy.GetIndexer(indexerMapping.RemoteIndexerId, Settings)
+                : null;
+
+            if (remoteIndexer != null)
+            {
+                _logger.Debug("Remote indexer {0} [{1}] found", remoteIndexer.Name, remoteIndexer.Id);
+
+                if (!quiIndexer.Equals(remoteIndexer) || forceSync)
+                {
+                    _logger.Debug("Syncing remote indexer with current settings");
+
+                    if (indexerCapabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray()).Any())
+                    {
+                        _quiProxy.UpdateIndexer(quiIndexer, Settings);
+                    }
+                    else
+                    {
+                        _quiProxy.RemoveIndexer(remoteIndexer.Id, Settings);
+
+                        if (indexerMapping != null)
+                        {
+                            _appIndexerMapService.Delete(indexerMapping.Id);
+                        }
+                    }
+                }
+            }
+            else
+            {
+                if (indexerMapping != null)
+                {
+                    _appIndexerMapService.Delete(indexerMapping.Id);
+                }
+
+                if (indexerCapabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray()).Any())
+                {
+                    _logger.Debug("Remote indexer not found, re-adding {0} [{1}] to qui", indexer.Name, indexer.Id);
+                    quiIndexer.Id = 0;
+                    var newRemoteIndexer = _quiProxy.AddIndexer(quiIndexer, Settings);
+
+                    if (newRemoteIndexer == null)
+                    {
+                        _logger.Debug("Failed to re-add {0} [{1}] to qui", indexer.Name, indexer.Id);
+                        return;
+                    }
+
+                    _appIndexerMapService.Insert(new AppIndexerMap { AppId = Definition.Id, IndexerId = indexer.Id, RemoteIndexerId = newRemoteIndexer.Id });
+                }
+                else
+                {
+                    _logger.Debug("Remote indexer not found for {0} [{1}], skipping re-add to qui due to indexer capabilities", indexer.Name, indexer.Id);
+                }
+            }
+        }
+
+        private QuiIndexer BuildQuiIndexer(IndexerDefinition indexer, IndexerCapabilities indexerCapabilities, int id = 0)
+        {
+            var supportedCategories = indexerCapabilities.Categories.SupportedCategories(Settings.SyncCategories.ToArray());
+
+            var capabilities = new List<string> { "search" };
+
+            if (indexerCapabilities.TvSearchAvailable)
+            {
+                capabilities.Add("tv-search");
+            }
+
+            if (indexerCapabilities.MovieSearchAvailable)
+            {
+                capabilities.Add("movie-search");
+            }
+
+            if (indexerCapabilities.MusicSearchAvailable)
+            {
+                capabilities.Add("music-search");
+            }
+
+            if (indexerCapabilities.BookSearchAvailable)
+            {
+                capabilities.Add("book-search");
+            }
+
+            return new QuiIndexer
+            {
+                Id = id,
+                Name = $"{indexer.Name} (Prowlarr)",
+                BaseUrl = $"{Settings.ProwlarrUrl.TrimEnd('/')}/{indexer.Id}/",
+                ApiKey = _configFileProvider.ApiKey,
+                Backend = "prowlarr",
+                Enabled = indexer.Enable,
+                Priority = indexer.Priority,
+                TimeoutSeconds = 30,
+                LimitDefault = 100,
+                LimitMax = 200,
+                IndexerId = indexer.Id.ToString(),
+                Capabilities = capabilities,
+                Categories = supportedCategories.Select(c => new QuiCategory { CategoryId = c, CategoryName = NewznabStandardCategory.GetCatDesc(c) }).ToList()
+            };
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/Qui/QuiException.cs b/src/NzbDrone.Core/Applications/Qui/QuiException.cs
new file mode 100644
index 000000000..02be1c757
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/Qui/QuiException.cs
@@ -0,0 +1,23 @@
+using System;
+using NzbDrone.Common.Exceptions;
+
+namespace NzbDrone.Core.Applications.Qui
+{
+    public class QuiException : NzbDroneException
+    {
+        public QuiException(string message)
+            : base(message)
+        {
+        }
+
+        public QuiException(string message, params object[] args)
+            : base(message, args)
+        {
+        }
+
+        public QuiException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/Qui/QuiIndexer.cs b/src/NzbDrone.Core/Applications/Qui/QuiIndexer.cs
new file mode 100644
index 000000000..3834d5da4
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/Qui/QuiIndexer.cs
@@ -0,0 +1,98 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Newtonsoft.Json;
+
+namespace NzbDrone.Core.Applications.Qui
+{
+    public class QuiCategory
+    {
+        [JsonProperty("indexer_id")]
+        public int IndexerId { get; set; }
+
+        [JsonProperty("category_id")]
+        public int CategoryId { get; set; }
+
+        [JsonProperty("category_name")]
+        public string CategoryName { get; set; }
+
+        [JsonProperty("parent_category_id")]
+        public int? ParentCategoryId { get; set; }
+    }
+
+    public class QuiIndexer : IEquatable<QuiIndexer>
+    {
+        [JsonProperty("id")]
+        public int Id { get; set; }
+
+        [JsonProperty("name")]
+        public string Name { get; set; }
+
+        [JsonProperty("base_url")]
+        public string BaseUrl { get; set; }
+
+        [JsonProperty("api_key")]
+        public string ApiKey { get; set; }
+
+        [JsonProperty("backend")]
+        public string Backend { get; set; }
+
+        [JsonProperty("enabled")]
+        public bool Enabled { get; set; }
+
+        [JsonProperty("priority")]
+        public int Priority { get; set; }
+
+        [JsonProperty("timeout_seconds")]
+        public int TimeoutSeconds { get; set; }
+
+        [JsonProperty("limit_default")]
+        public int LimitDefault { get; set; }
+
+        [JsonProperty("limit_max")]
+        public int LimitMax { get; set; }
+
+        [JsonProperty("indexer_id")]
+        public string IndexerId { get; set; }
+
+        [JsonProperty("capabilities")]
+        public List<string> Capabilities { get; set; }
+
+        [JsonProperty("categories")]
+        public List<QuiCategory> Categories { get; set; }
+
+        public bool Equals(QuiIndexer other)
+        {
+            if (ReferenceEquals(null, other))
+            {
+                return false;
+            }
+
+            var thisCategories = (Categories ?? Enumerable.Empty<QuiCategory>()).Select(c => c.CategoryId).OrderBy(c => c);
+            var otherCategories = (other.Categories ?? Enumerable.Empty<QuiCategory>()).Select(c => c.CategoryId).OrderBy(c => c);
+
+            var thisCapabilities = (Capabilities ?? Enumerable.Empty<string>()).OrderBy(c => c);
+            var otherCapabilities = (other.Capabilities ?? Enumerable.Empty<string>()).OrderBy(c => c);
+
+            return other.BaseUrl == BaseUrl &&
+                other.ApiKey == ApiKey &&
+                other.Name == Name &&
+                other.Backend == Backend &&
+                other.Enabled == Enabled &&
+                other.Priority == Priority &&
+                other.TimeoutSeconds == TimeoutSeconds &&
+                other.LimitDefault == LimitDefault &&
+                other.LimitMax == LimitMax &&
+                other.IndexerId == IndexerId &&
+                otherCapabilities.SequenceEqual(thisCapabilities) &&
+                otherCategories.SequenceEqual(thisCategories);
+        }
+
+        public override bool Equals(object obj) => Equals(obj as QuiIndexer);
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(BaseUrl, ApiKey, Name, Backend, Enabled, Priority, IndexerId);
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/Qui/QuiProxy.cs b/src/NzbDrone.Core/Applications/Qui/QuiProxy.cs
new file mode 100644
index 000000000..2924a59d3
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/Qui/QuiProxy.cs
@@ -0,0 +1,156 @@
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using FluentValidation.Results;
+using Newtonsoft.Json;
+using NLog;
+using NzbDrone.Common.Http;
+using NzbDrone.Common.Serializer;
+
+namespace NzbDrone.Core.Applications.Qui
+{
+    public interface IQuiProxy
+    {
+        QuiIndexer AddIndexer(QuiIndexer indexer, QuiSettings settings);
+        List<QuiIndexer> GetIndexers(QuiSettings settings);
+        QuiIndexer GetIndexer(int indexerId, QuiSettings settings);
+        void RemoveIndexer(int indexerId, QuiSettings settings);
+        QuiIndexer UpdateIndexer(QuiIndexer indexer, QuiSettings settings);
+        ValidationFailure TestConnection(QuiSettings settings);
+    }
+
+    public class QuiProxy : IQuiProxy
+    {
+        private const string AppIndexerApiRoute = "/api/torznab/indexers";
+
+        private readonly IHttpClient _httpClient;
+        private readonly Logger _logger;
+
+        public QuiProxy(IHttpClient httpClient, Logger logger)
+        {
+            _httpClient = httpClient;
+            _logger = logger;
+        }
+
+        public List<QuiIndexer> GetIndexers(QuiSettings settings)
+        {
+            var request = BuildRequest(settings, AppIndexerApiRoute, HttpMethod.Get);
+            return Execute<List<QuiIndexer>>(request);
+        }
+
+        public QuiIndexer GetIndexer(int indexerId, QuiSettings settings)
+        {
+            try
+            {
+                var request = BuildRequest(settings, $"{AppIndexerApiRoute}/{indexerId}", HttpMethod.Get);
+                return Execute<QuiIndexer>(request);
+            }
+            catch (HttpException ex)
+            {
+                if (ex.Response.StatusCode != HttpStatusCode.NotFound)
+                {
+                    throw;
+                }
+            }
+
+            return null;
+        }
+
+        public QuiIndexer AddIndexer(QuiIndexer indexer, QuiSettings settings)
+        {
+            var request = BuildRequest(settings, AppIndexerApiRoute, HttpMethod.Post);
+
+            request.SetContent(indexer.ToJson());
+            request.ContentSummary = indexer.ToJson(Formatting.None);
+
+            return Execute<QuiIndexer>(request);
+        }
+
+        public QuiIndexer UpdateIndexer(QuiIndexer indexer, QuiSettings settings)
+        {
+            var request = BuildRequest(settings, $"{AppIndexerApiRoute}/{indexer.Id}", HttpMethod.Put);
+
+            request.SetContent(indexer.ToJson());
+            request.ContentSummary = indexer.ToJson(Formatting.None);
+
+            return Execute<QuiIndexer>(request);
+        }
+
+        public void RemoveIndexer(int indexerId, QuiSettings settings)
+        {
+            try
+            {
+                var request = BuildRequest(settings, $"{AppIndexerApiRoute}/{indexerId}", HttpMethod.Delete);
+                _httpClient.Execute(request);
+            }
+            catch (HttpException ex)
+            {
+                if (ex.Response.StatusCode != HttpStatusCode.NotFound)
+                {
+                    throw;
+                }
+            }
+        }
+
+        public ValidationFailure TestConnection(QuiSettings settings)
+        {
+            try
+            {
+                GetIndexers(settings);
+            }
+            catch (HttpException ex)
+            {
+                _logger.Error(ex, "Unable to complete application test");
+
+                switch (ex.Response.StatusCode)
+                {
+                    case HttpStatusCode.Unauthorized:
+                        return new ValidationFailure("ApiKey", "API Key is invalid");
+                    case HttpStatusCode.NotFound:
+                        return new ValidationFailure("BaseUrl", "qui URL is invalid, Prowlarr cannot connect to qui. Is qui running and accessible?");
+                    default:
+                        return new ValidationFailure("BaseUrl", $"Unable to complete application test, cannot connect to qui. {ex.Message}");
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.Error(ex, "Unable to complete application test");
+                return new ValidationFailure("", $"Unable to complete application test. {ex.Message}");
+            }
+
+            return null;
+        }
+
+        private HttpRequest BuildRequest(QuiSettings settings, string resource, HttpMethod method)
+        {
+            var baseUrl = settings.BaseUrl.TrimEnd('/');
+
+            var request = new HttpRequestBuilder(baseUrl)
+                .Resource(resource)
+                .Accept(HttpAccept.Json)
+                .SetHeader("X-API-Key", settings.ApiKey)
+                .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);
+
+            if ((int)response.StatusCode >= 300)
+            {
+                throw new HttpException(response);
+            }
+
+            return Json.Deserialize<TResource>(response.Content);
+        }
+    }
+}
diff --git a/src/NzbDrone.Core/Applications/Qui/QuiSettings.cs b/src/NzbDrone.Core/Applications/Qui/QuiSettings.cs
new file mode 100644
index 000000000..a9e834b16
--- /dev/null
+++ b/src/NzbDrone.Core/Applications/Qui/QuiSettings.cs
@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using FluentValidation;
+using NzbDrone.Core.Annotations;
+using NzbDrone.Core.Indexers;
+using NzbDrone.Core.Validation;
+
+namespace NzbDrone.Core.Applications.Qui
+{
+    public class QuiSettingsValidator : AbstractValidator<QuiSettings>
+    {
+        public QuiSettingsValidator()
+        {
+            RuleFor(c => c.BaseUrl).IsValidUrl();
+            RuleFor(c => c.ProwlarrUrl).IsValidUrl();
+            RuleFor(c => c.ApiKey).NotEmpty();
+            RuleFor(c => c.SyncCategories).NotEmpty();
+        }
+    }
+
+    public class QuiSettings : IApplicationSettings
+    {
+        private static readonly QuiSettingsValidator Validator = new();
+
+        public QuiSettings()
+        {
+            ProwlarrUrl = "http://localhost:9696";
+            BaseUrl = "http://localhost:7476";
+            SyncCategories = new[] { 2000, 3000, 4000, 5000, 6000, 7000, 8000 };
+        }
+
+        [FieldDefinition(0, Label = "Prowlarr Server", HelpText = "Prowlarr server URL as qui sees it, including http(s)://, port, and urlbase if needed", Placeholder = "http://localhost:9696")]
+        public string ProwlarrUrl { get; set; }
+
+        [FieldDefinition(1, Label = "qui Server", HelpText = "URL used to connect to qui server, including http(s)://, port, and urlbase if required", Placeholder = "http://localhost:7476")]
+        public string BaseUrl { get; set; }
+
+        [FieldDefinition(2, Label = "API Key", Privacy = PrivacyLevel.ApiKey, HelpText = "The ApiKey generated by qui in Settings")]
+        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));
+        }
+    }
+}