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AspenDev

A zero-dependency developer toolbox — 9 offline tools for everyday dev work, from crypto to regex.

Downloads See the tools

Version 1.1.0 · Windows 10/11 · 64-bit · Free

AspenDev — sidebar of 9 developer tools on the left, the encrypt/decrypt tool open on the right (dark theme)
Tools
9 tools, one window — all offline
🔒

Encrypt / Decrypt

Password-based AES-256-GCM. Encrypt text and keep it as armored text; decrypt later with the same password.

🧮

Hash / Checksum

SHA-256/384/512, SHA-1, MD5 — of text or a file's raw bytes. Matches sha256sum / Get-FileHash.

⇄

Base64

Encode text to Base64 or decode it back, with an optional URL-safe alphabet.

{ }

JSON Format

Validate and pretty-print JSON, or minify it to a single line.

🎫

JWT decoder + verify

Decode header/payload, render exp/iat/nbf as dates, and verify HS/RS/ES signatures — offline.

🏷️

UUID Generator

v4 (random) and v7 (time-ordered). Choose the count, format and case.

🕐

Timestamp

Convert between a Unix timestamp and a date — local, UTC and ISO-8601.

🔑

Password Generator

Strong random passwords from a cryptographic RNG, with length and character-set options.

🔍

Regex Tester

.NET-flavor regex: matches, capture groups, replacement — plus a 20-entry cheat sheet.

Command palette (Ctrl+K) to jump to any tool. Everything runs locally — no server calls, tracking or collection. Zero external libraries.

Themes
Five built-in themes
AspenDev — Dark theme
Dark
AspenDev — Light theme
Light
AspenDev — BTS theme
BTS
AspenDev — Green theme
Green
AspenDev — Blue theme
Blue
Compact mode
Dock to a slim bar

Collapse the window to a slim, always-on-top bar pinned to the top of your screen — your tools are a double-click away.

AspenDev compact-mode bar, dark theme
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Get it now

Choose the installer (recommended) or the no-install portable build.

Installer (.exe · 57MB) Portable (.zip · 56MB)
Requirements: Windows 10/11 (64-bit) · runs even without .NET installed (runtime bundled)
Changelog
Changelog
VersionNotes
1.1.0
2026-07		 AspenKit family integration (launch siblings, cross-app compact tiling, cross-app magnetic snap). Stability: heavy work (PBKDF2 key derivation, large-file hashing) moved off the UI thread to prevent freezes; edge-input exception guards (JWT/timestamp), regex-replace fidelity, durable settings writes; build version single-sourced.
1.0.0
2026-07		 First public release. Nine offline tools — encrypt/decrypt (AES-256-GCM), hash/checksum, Base64, JSON, JWT decode+verify (HS/RS/ES), UUID (v4/v7), timestamp, password generator, and a .NET regex tester with a 20-entry cheat sheet. Five themes (dark/light/BTS/green/blue), Korean/English, command palette, magnetic window snap, compact mode, always-on-top pin, and settings persistence. Installer & portable builds.