Nymble

Nymble is a self-hosted web app that replaces sensitive details in text with simple placeholders before you share it with AI, then restores them later. After replacement, it uses Presidio to highlight possible leaks.

Nymble does not send text to an AI service. You remain in control of where the depersonalized result is copied and which AI tool receives it.

What it does

Nymble uses dictionaries that map semantic placeholders to one or more real values:

John Smith    -> {CEO}
Acme Ltd      -> {T company}

The first value is the primary value used when restoring placeholders. Other values act as aliases during depersonalization.

real text
  -> dictionary replacement
  -> depersonalized text
  -> Presidio analysis
  -> visual leak highlights

Presidio findings are visual only: Nymble does not automatically remove or replace them. The copied result remains clean text without highlight markup.

Using Nymble

1. Open Edit dictionaries and create placeholders for people, companies, projects, addresses, or any other values you do not want to share.
2. Return to the composer and choose a dictionary as the destination.
3. Paste or type the original text in the left editor.
4. Select the Presidio analysis language, or select off to skip leak detection for that transform.
5. Review the depersonalized result. Possible leaks are highlighted in red.
6. Copy the clean result and send it to the AI tool of your choice.
7. Paste the AI response into Nymble, reverse the direction, and restore the placeholders to their primary dictionary values.

On a new installation, the bundled {Work} dictionary is selected and the source editor shows one fictional sentence that demonstrates depersonalization. It intentionally leaves Paris out of the dictionary so Presidio can demonstrate a possible leak highlight. The example is intended for a first look and screenshots. Clearing or changing the text, or changing the transformation direction, records a browser cookie so the example is not shown again.

Clipboard support

The source editor has a Paste button and the result editor has a Copy button. Clipboard access depends on browser permission and requires a secure context: use HTTPS in production, or localhost during local development. Keyboard copy and paste remain available if browser clipboard permission is not granted.

Install as an app

Nymble includes a web app manifest and platform icons, so it can be installed for quicker access:

• Windows: open Nymble in Microsoft Edge, then choose Settings and more → Apps → Install this site as an app. See the Microsoft Edge installation guide.
• Android: open Nymble in Chrome, then choose More → Add to Home screen → Install. See the Google Chrome web app guide.
• iPhone and iPad: open Nymble in Safari, choose Share → Add to Home Screen, enable Open as Web App, and tap Add. See the Apple installation guide.

The installed app still connects to your Nymble server. Offline operation is not currently supported because Nymble does not install an offline service worker. HTTPS is recommended and may be required by the browser for app installation and clipboard access.

Screenshots

Leak review	Dictionary editor	Installed app

Fully self-hosted

Both Nymble and Presidio run on infrastructure you control. The default Docker Compose configuration exposes Nymble only on 127.0.0.1:3100 and keeps Presidio entirely inside the Compose network. Presidio has no public host port.

Dictionary data is stored in the runtime data/ directory and bind-mounted into the Nymble container. It is not stored in a hosted Nymble service because there is no hosted Nymble service.

For production use, place Nymble behind an HTTPS reverse proxy and an authentication layer appropriate for your environment. Nymble itself does not currently provide user accounts or access control. Treat the dictionary file as sensitive data and include it in your backup and access-control policy.

Presidio uses automated detection and cannot guarantee that it will find every sensitive value. Always review the result before sharing it.

System requirements

Nymble is deployed with Docker Compose and includes the Presidio Analyzer container. The figures below are practical starting points rather than hard limits; actual usage depends on text size, traffic, the Presidio image, and enabled language models.

Resource	Practical minimum	Recommended
CPU	2 vCPU	2 or more vCPU
RAM	2 GiB plus swap	4 GiB RAM
Swap	2 GiB	2 GiB
Free disk	8 GiB	15 GiB or more
OS	Linux with Docker Engine	Current Debian or Ubuntu LTS

The current deployment has been tested on a 2-vCPU VPS with 4 GiB RAM and 2 GiB swap. Presidio used approximately 766 MiB RAM during testing; Compose caps the analyzer container at 1200 MiB.

Required host tools:

• Git;
• Docker Engine;
• the Docker Compose plugin (docker compose);
• Bash and curl.

Node.js is not required on the host when running ops/deploy.sh directly; Node.js and all build dependencies are provided by the Docker build stages.

Installation

Clone the repository wherever you keep source checkouts:

git clone https://github.com/SergeyXa/nymble.git ~/code/nymble
cd ~/code/nymble

Build and deploy Nymble:

sudo ./ops/deploy.sh

The deploy script:

1. builds a versioned Nymble image from the current working tree;
2. creates the runtime directory at /srv/nymble by default;
3. seeds the first runtime dictionary from the tracked example in data/dictionaries.json, then preserves data in /srv/nymble/data;
4. installs the runtime Compose file and configuration;
5. starts Nymble and Presidio;
6. checks http://127.0.0.1:3100/api/health;
7. removes older Docker images belonging specifically to Nymble.

Verify the installation:

curl http://127.0.0.1:3100/api/health
curl http://127.0.0.1:3100/api/config

The default endpoint is intended for a local reverse proxy. To choose a different runtime path, port, bind address, Presidio resource limit, or leak detection configuration, see Docker deployment and configuration.

Updating

cd ~/code/nymble
git pull --ff-only
sudo ./ops/deploy.sh

The runtime .env and data/ directory are preserved across deployments.

Technology stack

• Node.js 24 and TypeScript for the application server and shared types;
• Fastify for HTTP routes, static assets, and JSON APIs;
• React for the composer and dictionary editor;
• CodeMirror 6 for text editing and visual annotations;
• Bootstrap and Bootstrap Icons for layout and controls;
• esbuild for the browser bundle;
• Presidio Analyzer for possible leak detection after dictionary replacement;
• Docker and Docker Compose for reproducible builds and self-hosted deployment.

Dictionary storage is intentionally simple: a JSON file in the persistent runtime data directory. There is no external database.

Repository layout

src/
  client/
    composer/       main text transformation UI
    dictionaries/   dictionary management UI
  server/
    services/       Presidio client and leak-detection abstraction
    templates/      HTML document shells
    config.ts       environment configuration
    dictionaryStore.ts
    transform.ts    reversible dictionary transformation
media/              PWA manifest, icons, and platform assets
test/               automated unit tests
ops/                deploy script, runtime env template, operations guide
data/dictionaries.json  tracked example dictionaries; seed for a new deployment
Dockerfile          multi-stage production image
docker-compose.yml  Nymble and internal Presidio services

The backend transforms text first and sends only the final depersonalized text to Presidio. Presidio findings are normalized, filtered by score, and resolved for overlaps before the browser renders them as annotations.

Development

For local development with Node.js 24 or newer:

npm install
cp .env.example .env.dev
npm run build
npm start

Useful commands:

npm test
npm run dev
npm run build
npm start

npm start loads .env.dev when it exists. npm run dev uses environment variables exported by the current shell. The example dictionary is tracked; runtime data other than that example, local environment files, build output, and dependencies are ignored by Git.

License, copyright, and trademarks

Nymble is released under the MIT License, Copyright © 2026 Sergey Kharchenko. You may use, modify, distribute, sublicense, and sell copies of the software. Copies or substantial portions of the software must retain the copyright notice and permission notice from the license.

Nymble uses the independently maintained Presidio project through its official analyzer container. Presidio is licensed under the MIT License, Copyright © Presidio Contributors. Presidio remains subject to its own license and notices; Nymble is not affiliated with or endorsed by the Presidio contributors.

JavaScript dependencies retain their own licenses. The current dependency tree contains packages under MIT, BSD-3-Clause, ISC, Apache-2.0, and BlueOak-1.0.0 licenses. Consult package-lock.json and each installed package's license metadata before redistributing a built image or binary bundle.

Microsoft, Windows, and Microsoft Edge are trademarks of the Microsoft group of companies. Apple, iPhone, iPad, iOS, and Safari are trademarks of Apple Inc. Android and Google Chrome are trademarks of Google LLC. Docker is a trademark of Docker, Inc. All other product names and trademarks belong to their respective owners and are used only for identification. Their mention does not imply affiliation with or endorsement of Nymble.