rtl_tcp SDR vs Gridi
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
rtl_tcp SDR
This app acts as a software-defined radio receiver for iOS devices, allowing you to listen to various radio signals and view RF spectrum data. It connects to external SDR peripherals via a network protocol, requiring a separate server setup.
- Listen to AM, FM, SSB, CW signals
- View RF spectrum and waterfall
- Connect to networked RTL-SDR peripherals
- Supports Airspy HF+, SDRPlay, LimeSDR Mini
- Direct connection to Hermes Lite 2
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An RTL-SDR Software Defined Radio receiver app for iOS devices. Listen to AM, FM, SSB and CW radio signals. View an RF spectrum and waterfall. Connect, via the rtl_tcp network protocol, to networked RTL-SDR USB peripherals. This app requires an external rtl_tcp server. iOS devices do not currently support the direct connection of USB peripherals such as an RTL-SDR. Thus, the use of this app requires network access to a server, such as a Raspberry Pi (or Mac), with an RTL-SDR unit plugged into its USB port, and running the rtl_tcp protocol at an TCP/IP network address accessible from your iOS device. This allows a Raspberry Pi (or Mac) to act, essentially, as the USB port adapter for your iOS device. The rtl_tcp SDR app can also connect to hfp_tcp for the Airspy HF+, rsp_tcp for SDRPlay devices, and lmm_tcp for the LimeSDR Mini; see GitHub for server source code. This app can also connect to a Hermes Lite 2 QRP transceiver directly, if it has a known IP address, or through an hl2_tcp server. No support is provided for installing any of the rtl_tcp or other tcp software needed to use this app (with a Raspberry Pi, or otherwise). Please do not download this app unless you are already familiar with Software Defined Radio, have an RTL-SDR or equivalent USB SDR peripheral, and have already installed and tested rtl_tcp on your Raspberry Pi, Mac, or other server. Note that this app requires a very high bandwidth network connection in order to receive streams of real-time RF samples from an RTL-SDR. It is recommended that your rtl_tcp server be on a wired connection rather than on the same WiFi as your iOS device.
Gridi
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Gridi is a smart energy monitoring app designed for home users. It provides real-time monitoring of solar power generation, battery storage, EV charging, and heat pump operation in residential energy systems. With Gridi, homeowners can stay informed of their energy usage and optimize it for efficiency and sustainability. Key Features: Real-time monitoring of PV, battery, EV charger, and heat pump systems Supports various energy modes: self-consumption, peak shaving, backup, and more Remote access via smartphone with clear, user-friendly data display Multilingual interface designed for global home users Who is it for: Homeowners with solar, battery, EV charging, or heat pump systems.
Screenshots
Verdict
The clearest difference is price: Gridi at Free against rtl_tcp SDR's $12.99. Gridi also leads on update cadence (every 2 weeks vs every 4 months) and iOS requirement (13.0 vs 16.6). rtl_tcp SDR's advantage is chart position (#191 vs unranked). On ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Gridi is free to download; rtl_tcp SDR costs $12.99 up front. Neither carries in-app purchases, so what you see is what you pay.
rtl_tcp SDR ships an update every 4 months, Gridi every 2 weeks. The most recent releases landed on October 16, 2026 and October 8, 2026 respectively.
| Parameter | rtl_tcp SDR | Gridi |
|---|---|---|
| Price | $12.99 | Free — better |
| Rating | 3.9 (32 ratings) — better | — |
| Positive reviews | 40.0% of reviews | — |
| Number of ratings | 32 — better | — |
| Update frequency | Every 4 months | Every 2 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | — |
| Best chart rank | #191 — better | — |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 16.6 | 13.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 18 MB |
| Age rating | 4+ | 17+ |
| Developer | HotPaw Productions | Solareast heat pump co.,Ltd |
In-app purchases
rtl_tcp SDR
No in-app purchases
Gridi
No in-app purchases









