📡 IoT Ephemeral Value Store

Temporarily store and retrieve sensor values via plain HTTP — no registration, no setup.

🔍 Viewer & Key Manager

Monitor live values, manage your key pairs, and inspect all stored data in one place.

Open Viewer →
Your personal key pair (generated for this page load)
🔑 Upload Key  (keep secret)
u_ae7c782ec790e8809fa7543363c1d52f5d4f846da950ec0e20cca6f67aa0dfdf
Used to write & delete data. Never share this key.
📥 Download Key  (shareable)
d_643809731f8f4d0919f25d838db80a42310e5e81a0c3384219234d6df439a88c
Read-only. Safe to share with dashboards, Home Assistant, etc.
💡 Generate a permanent key pair anytime: GET /kp  —  bookmark the result and reuse the keys across all your devices.
1 · Upload data

⬆️ Upload — replace all values at once

Send any number of key=value pairs as query parameters. Each upload replaces all previously stored values.

via browser

via curl (works from any microcontroller or script)

curl "/u/u_ae7c782ec790e8809fa7543363c1d52f5d4f846da950ec0e20cca6f67aa0dfdf/?temp=23&hum=45"
2 · Patch data (merge from multiple devices)

🔀 Patch — merge values from multiple sources

Unlike a plain upload, Patch keeps all existing values and only updates the fields you provide. Use an optional path segment to namespace values from different devices or rooms under the same upload key.

sensor_a
temp=23
+
sensor_b
voltage=230
→
merged JSON
temp=23, voltage=230

via curl

# Room 1 sensor pushes temperature
curl "/patch/u_ae7c782ec790e8809fa7543363c1d52f5d4f846da950ec0e20cca6f67aa0dfdf/living_room/?temp=23&hum=45"

# Room 2 sensor pushes voltage independently
curl "/patch/u_ae7c782ec790e8809fa7543363c1d52f5d4f846da950ec0e20cca6f67aa0dfdf/basement/?voltage=230"

# Deeply nested paths are supported too
curl "/patch/u_ae7c782ec790e8809fa7543363c1d52f5d4f846da950ec0e20cca6f67aa0dfdf/house_2/floor1/room3/?co2=420"
All three calls use the same upload key but different path namespaces. The download key returns a single merged JSON containing all values.
3 · Download data

⬇️ Download — read values

Single value (plain text)

Ideal for Home Assistant rest sensors or simple shell scripts.

curl "/d/d_643809731f8f4d0919f25d838db80a42310e5e81a0c3384219234d6df439a88c/plain/temp"

All values (JSON)

Returns the complete merged data object.

curl "/d/d_643809731f8f4d0919f25d838db80a42310e5e81a0c3384219234d6df439a88c/json"

Delete data (or just wait for the retention period to expire)

Advanced · Base64 encoding

🔡 Base64URL values

Upload values base64url-encoded and let the server decode them on download — useful for values containing special characters.

Upload (base64url encoded value)

Download (server decodes automatically)

The download key is derived from the upload key: strip the u_ prefix, then SHA-256 hash it.
echo -n "5347d61e..." | sha256sum
MCP Integration

🤖 Model Context Protocol (MCP)

This server exposes an MCP endpoint. Add it to VS Code, Claude Desktop, or any MCP-compatible client:

{
  "mcpServers": {
    "IoT-Ephemeral-Value-Store-Server": {
      "type": "http",
      "url": "https://iot.hdev.io/mcp",
      "headers": {},
      "tools": ["*"]
    }
  }
}
Server information

⚙️ Settings

Version
v1.0.16
Build time
2026-02-21_21:59:19
Data retention
24h
Uptime
523h53m44.593482404s

📊 Stats (REST API)

Downloads / Uploads (total)
921 / 95381
Downloads / Uploads (24h)
1 / 4196
HTTP errors (total / 24h)
339 / 337
Rate limit hits
0

📊 Stats (MCP)

Downloads / Uploads (total)
10 / 7
Downloads / Uploads (24h)
0 / 0
HTTP errors (total / 24h)
3 / 0

🚦 Rate-limited IPs

No rate-limited IPs.

IoT Ephemeral Value Store on GitHub