.NET Code Tips
The .NET Developer Toolbox
Free utilities for the things .NET developers search for every week — generating C# from JSON, migrating web.config, testing timer schedules, decoding tokens. Each one runs entirely in your browser.
JSON to C# record & class generator
Paste any JSON payload and get strongly typed C# records or classes, with [JsonPropertyName] attributes, nullable types, List<T> collections, DateTime and Guid detection, and an optional source-generated JsonSerializerContext.
Open the toolweb.config to appsettings.json converter
Migrating from ASP.NET MVC 5 or Web API 2 to ASP.NET Core? Paste a web.config and get the equivalent appsettings.json — appSettings, connectionStrings, colon-delimited sections — plus a checklist of the system.web settings that move into code.
Open the toolNCRONTAB & Azure Functions timer builder
Build, explain and test the six-field NCRONTAB expressions used by Azure Functions TimerTrigger and WebJobs. See the schedule in plain English and the next run times in UTC or any time zone, with a gallery of common presets.
Open the toolWindows ↔ IANA time zone ID lookup
"Eastern Standard Time" or "America/New_York"? Search every Windows time zone ID and its IANA equivalents from the Unicode CLDR mapping, with the current UTC offset and daylight saving status, and the TimeZoneInfo code to convert them.
Open the toolJWT decoder & claims inspector
Paste a bearer token to see its header and payload, every claim explained — including the long Microsoft and Entra ID claim URIs — and exp, nbf and iat as real dates. Optionally verify an HS256 signature. The token never leaves your browser.
Open the toolGUID / UUID generator & inspector
Generate random v4 or time-ordered v7 GUIDs (the kind Guid.CreateVersion7 makes in .NET 9) in bulk, in every Guid.ToString format — N, D, B, P and X. Paste one to see its version, variant and embedded timestamp.
Open the toolBase64 & Base64Url encoder / decoder
Encode or decode text as UTF-8 Base64 or URL-safe Base64Url, turn a file into a Base64 string, see the hex bytes, and convert a GUID to the 22-character short form — matching what Convert.ToBase64String produces.
Open the toolConnection string builder & parser
Build connection strings for SQL Server (Microsoft.Data.SqlClient, including Entra ID authentication and Encrypt/TrustServerCertificate), PostgreSQL, SQLite and Azure Storage — or paste one to break it apart. Copy it raw, as appsettings.json, or as a C# string.
Open the toolCSV preview that handles quoted commas
Paste or drop a CSV file and see it as a table, parsed properly: quoted fields with embedded commas, line breaks and doubled quotes. Auto-detects the delimiter, and exports JSON, a C# record, or a SqlBulkCopy loader for SQL Server.
Open the tool.NET format string tester
Try DateTime, DateTimeOffset, int, double and decimal format strings — "yyyy-MM-dd", "o", "N2", "C", "#,##0.00;(#,##0.00)" — in 14 cultures and see exactly what ToString prints, token by token, checked against real .NET output.
Open the tool.NET exception stack trace cleaner
Paste an exception from a log and get the root cause, the line in your code that threw, and a readable trace — async state machines, lambdas and local functions demangled, framework and await noise collapsed. Nothing leaves your browser.
Open the tool.NET versions, support dates & target frameworks
Every .NET, .NET Core and .NET Framework release with its end-of-support date and latest patch, plus a target framework reference: the default C# version, the #if symbols and the .NET Standard version each TFM can use.
Open the toolLooking for an old tip?
.NET Code Tips started in 2016 as a collection of short how-to articles for ASP.NET MVC 5 and .NET Framework. Those articles described APIs that have since been replaced, so the site is now a set of tools instead — and the most-read tips live on inside them. Posting JSON with HttpClient is covered on the JSON to C# page, reading CSV files with embedded commas and bulk-loading them with SqlBulkCopy on the CSV viewer, and RedirectToAction, rewrite rules and custom errors in the ASP.NET Core migration guide. Old links redirect to the closest tool automatically.