Add blog post for Dev Proxy v2.3.4 release with accurate HAR timestamps

Co-authored-by: Copilot <copilot@github.com>

Author: waldekmastykarz

public/blog/images/v2-3-4.png

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+---
+title: "Dev Proxy v2.3.4 with accurate HAR timestamps"
+description: "Dev Proxy v2.3.4 fixes HAR entry timestamps to reflect actual request times in proper UTC format, making your API recordings more reliable."
+date: 2026-04-23
+author: "Waldek Mastykarz, Garry Trinder"
+tags: ["release"]
+image: "/blog/images/v2-3-2.png"
+---
+
+We've just released **Dev Proxy v2.3.4** - a cleanup release that perfects the HAR timestamp fix introduced in v2.3.3.
+
+**In this version:**
+
+- Fixed HAR entry timestamps to reflect actual request times in proper UTC format
+
+## Accurate HAR timestamps
+
+When Dev Proxy generates HAR files, each entry includes a `startedDateTime` field that records when the request was made. Before v2.3.3, this timestamp was set at HAR export time - meaning all entries showed the same time regardless of when the requests actually happened. Not great when you're trying to analyze request timing or debug race conditions.
+
+In v2.3.3, we fixed this by recording the actual request timestamp. However, the fix introduced a subtle formatting issue - timestamps used the `+00:00` offset format instead of the standard `Z` UTC suffix that HAR tooling expects.
+
+In v2.3.4, we've cleaned this up. HAR entry timestamps now correctly use the `Z`-suffixed UTC format, giving you accurate request times in the format that tools expect.
+
+If you're analyzing request sequences, debugging timing-sensitive issues, or feeding HAR data into monitoring tools, you now get timestamps that reflect when each request actually happened - not when you exported the file.
+
+## Dev Proxy Toolkit
+
+[Dev Proxy Toolkit](https://marketplace.visualstudio.com/items?itemName=garrytrinder.dev-proxy-toolkit) is an extension that makes it easier to work with Dev Proxy from within Visual Studio Code. Alongside the new release of Dev Proxy, we've also released a new version of the toolkit, v1.20.0.
+
+In this version, we've:
+
+- Updated all JSON snippets to use v2.3.4 schemas
+
+Checkout out the [changelog](https://marketplace.visualstudio.com/items/garrytrinder.dev-proxy-toolkit/changelog) for more information on changes and bug fixes.
+
+## Try it now
+
+Download Dev Proxy v2.3.4 today and get accurate HAR recordings for your API testing workflows!
+
+Got feedback or ideas? [Join us](https://github.com/dotnet/dev-proxy/discussions) and be part of the conversation.