Pure Upright vs StringLab
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Pure Upright
This app offers a virtual upright piano experience with a unique Morph Pad for blending timbres. It functions as a standalone app or AUv3 plugin and connects to MIDI controllers for professional sound creation.
- Morph Pad for timbre blending
- Standalone app and AUv3 plugin
- MIDI controller connectivity (USB, Bluetooth)
- Customizable reverb, EQ, and delay
- Sympathetic resonance and key noise
- Flexible tuning options
- Velocity response customization
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An upright piano sits perfectly in pop, R&B, Hip-Hop, and many more modern music genres. That’s why it’s heard in countless iconic tracks throughout musical history with the upright at the heart of the song. You don’t always need the splendor of a grand piano but the character and immediacy of an upright piano. Pure Upright captures the uniquely recognizable sound of the upright piano and makes it as wonderfully playable as our acclaimed Pure Piano for iOS. Similar to an XY pad in its flat, tactile nature, the Morph Pad offers up nine different core upright piano timbres, including Vintage, Intimate, Reverse, Gated, and Pad, to name a few. The “pure” Upright sits untouched at the heart and center of the space, surrounded by eight more presets for you to explore as you guide your finger seamlessly through the wide-ranging tonal palette of the piano. As you do so, the various timbres blend together, allowing you to create your own sounds comprising combinations of neighboring presets for you to save and recall. Pure Upright works as a standalone app or as an AUv3 plug-in within your DAW of choice, and extensive connectivity options allow you to easily connect to your keyboard controller via USB, direct, or Bluetooth MIDI to experience the sound of a professional grand piano through your headphones or speakers. The app also supports a direct connection to your Mac using Inter Device Audio (IDAM). This enables you to easily integrate Pure Upright into your desktop projects by sending MIDI and receiving audio with one single cable, as well as network MIDI and Inter-App Audio for triggering the piano from other apps that you might have installed. Equipped with customizable reverb, EQ, and delay, sound creation becomes even more creative. Simply unlink any of the audio effects from the Morph Pad to dial in your own settings. Maybe you want to add a long reverb tail to add some extra atmosphere, tweak the EQ a little or add some delay to a particular sound. It’s up to you. If all that isn’t enough, the app includes sympathetic resonance which you can adjust along with the pedal and key noise to taste, and there’s a host of flexible tuning options for when you need them. The stretched piano tuning is how a piano technician would tune the piano. The equal temperament tuning, on the other hand, is best for when layering Pure Upright with sounds like electric pianos, pads, or strings. Also provided is the ability to transpose the piano which comes in very useful if you are working with a vocalist who wants to sing in a different key! For the best experience with Pure Upright, we highly recommend using a controller keyboard to trigger the notes so that it feels like you’re playing a real upright piano. The on-board velocity response page allows you to match the dynamic response of Pure Upright to your keyboard controller and your playing style so that you can achieve the right velocity response for you and the song you’re playing. Pure Upright is designed and developed by Hamburg-based e-instruments, renowned for their high-end digital recreations of acoustic instruments. Feature Overview: - Interactive Morph Pad - Explore the different characteristics of the upright piano - Nine different sounds - Navigate and blend between nine core sounds - Studio Quality Audio at Ultra-low Latency - Extensive Connectivity - Connect via USB, direct, or Bluetooth MIDI. Inter Device Audio (IDAM), Network MIDI, and Inter-App Audio also fully supported - Standalone and AUv3 plug-in compatible - Zynaptiq QREV Reverb - Have fun adding extra atmosphere and depth to your sound - 3-Band EQ and Delay - Get creative with customizable EQ and Delay, or use the Morph Pad as a macro control - Save, Load & Share Your Own Sound Presets - Sympathetic Resonance - Silent Key Press - Flexible Tuning Options - Customizable velocity curve - 24-bit, 44.1 kHz - 1.1GB installation
StringLab
This app is a digital synthesizer that uses physical string modeling to recreate the sounds of various instruments, particularly plucked or hammered strings. It allows users to explore acoustic physics and create unique instrument textures through extensive parameter experimentation.
- Karplus-Strong physical modeling
- Exciter Impact and Noise modes
- Resonator objects with feedback
- Frequency Dispersion support
- External live input
- Preset randomizer and manager
- Drag & Drop preset export
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StringLab is a physical string modeling synthesizer based on Karplus-Strong theory. It is capable of reproducing the sounds of many different types of instruments, but is especially useful in the reproduction of hammered or plucked strings and other types of percussive instruments. It works by passing carefully crafted waveforms and short bursts of white noise through a series of tuned delay lines. The delay lines have an internal feedback loop with a series of filters to mimic the natural decay of harmonics found in a real instrument. StringLab allows you to discover the character of real-world accoustics, exploring the physics of how materials interact. Many new and original textures are born out of experimenting with the settings, so don't be afraid to experiment and create your own unique and dynamic instruments. Features •Karplus Strong based physical modeling. •Exciter Impact with multiple modes. •Exciter Noise with many envelope driven filters. •2 resonator objects with feedback. •8 bands per object with inversion. •4 Coupling modes. •Supports Frequency Dispersion. •Feedback low/high Damping. •Per object Body Filter. •Pitch Deformity. •External live input mode. •Preset randomiser. •Build it Preset Manager & Favourites. •Search Presets. •Drag & Drop preset export of presets. •Supports Color Sets.
Screenshots
Verdict
The clearest difference is price: StringLab at $14.99 against Pure Upright's $29.99. StringLab also leads on update cadence (every 10 days vs every 3 months) and iOS requirement (13.0 vs 15.0). Pure Upright's advantage is rating (4.9 vs 4.3) and review sentiment (75% vs 57%). On ads, in-app purchases, monetization model 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
Pure Upright costs $29.99 and StringLab $14.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Pure Upright holds the better App Store score, 4.9 against 4.3. That said, the two scores are not equally well evidenced: Pure Upright has 72 ratings behind it against 14, so its average is the more settled of the two. Written reviews point the same way: 75% of Pure Upright's written reviews are positive against 57% of StringLab's.
Pure Upright ships an update every 3 months, StringLab every 10 days. The most recent releases landed on September 26, 2026 and September 25, 2026 respectively.
| Parameter | Pure Upright | StringLab |
|---|---|---|
| Price | $29.99 | $14.99 — better |
| Rating | 4.9 (72 ratings) — better | 4.3 (14 ratings) |
| Positive reviews | 75.0% of reviews — better | 57.1% of reviews |
| Number of ratings | 72 — better | 14 |
| Update frequency | Every 3 months | Every 10 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 13.0 — better |
| Further details — not scored | ||
| Size | 1.2 GB | 45 MB |
| Age rating | 4+ | 4+ |
| Developer | e-instruments lab GmbH | 4Pockets.com |
Customer experience
Pure Upright
StringLab
In-app purchases
Pure Upright
No in-app purchases
StringLab
No in-app purchases









