What is Red Ink?
It is an add-in for Microsoft Office on Windows that allows you to access your preferred large language models (LLM) directly within Word, Excel and Outlook, enabling you to use the power of AI in a variety of ways in your daily work - right where you work, without having to switch to a browser and directly from within your documents, worksheets and emails:
- You can select a text or cells in your worksheet and have the content translated, corrected or improved in various ways.
- You can have summaries created, automatically abbreviate or anonymise text, or ask the AI to comment on your document according to your specifications (using Word comments/bubbles) or to analyse specific revisions to your document (‘What did the other side summarise and change?’).
- You can have Word bubble comments automatically applied to your text, either those manually created or the ones automatically generated by Red Ink.
- With one click, you receive an overview of the most important aspects of extensive texts, created within seconds by your AI.
- There is a context search (a search for ‘liability’, for example, not only finds ‘liability’ but also related passages such as ‘we are not liable’).
- There is a chatbot integrated into Word which can also edit your text directly if you wish.
- You can have live transcription created from meetings and dictations are also possible (with post-processing by the AI and the possibility to give special instructions like "Create three letters for me from this text, where the first … ").
- You can write free prompts or access a prompt library with complex prompts, you can combine external documents with your own text (including searchable PDFs.)
- You can link a text database and use it to revise your documents (Mini-RAG).
- You can have the AI create formulas and content for cells in Excel (‘Insert the formulas for a linear regression for the following case:...’) or have it filled in (‘Complete C10:C20 with suggestions for answers to the questions in B10:B20 based on the use case in C9’). If your model is advanced, you can also have more complex forms filled out fully automatically.
- You can get an overview of your latest e-mails with one click or have a long e-mail chain summarised.
- You can have the AI create a suggested reply for your email – even for complex requests.
- If your model supports this, you can extract any elements from a PDF, whether tables, specific sections, or have them analyzed – even if the PDF is not searchable.
- With a click, you can have the AI transcribe or describe a screenshot (created, for example, via Shift-Windows-S, e.g., part of your document that cannot be copied), an audio file (e.g., a voicemail), or an image.
- You can access any number of language models (they are easy to configure), including language models with reasoning for more complex questions and with internet search (such as Perplexity) or even deep research reports – directly in Word, ready for further processing.
- You have direct access to any number of configurable databases and AI services, e.g., to search directly from your text for relevant court decisions; you can then have the AI automatically insert the hits into your text (e.g., LexiSearch, Entscheidsuche.ch, LexFind, FragdenOK).
- If suggestions for changes are made, you can also receive these as markup – not only in Word, but also in Outlook, although Outlook does not actually support this. Red Ink also goes further than many other tools when it comes to preserving formatting (such as bold, footnotes, fields).
- There is a browser extension so that you can use Red Ink in your Chromium-based browser (Edge, Chrome) (e.g. to search the content of webpages or PDFs using AI) or to translate or correct texts that you are supposed to fill out in a form.
- You can have your texts converted into audiobooks and podcasts, similar to Google's NotebookLM function (this requires a Google Cloud Platform or OpenAI account, though).
- You can have presentations in Powerpoint created fully automatically from any text, including speaker notes – and also have them translated into audio (using Google or OpenAI). This can be used to generate videos of your presentations. This also works with your own templates.
- If your models support this, you can have images created or even edited;
- On request, Red Ink can also automatically anonymize texts based on text lists (e.g. with client names) before they are transferred to the AI; the plain text terms are automatically reinserted in the result;
- If you don't like the AI's writing style, you can train Red Ink to use your own writing style (or multiple styles) based on Word documents and emails.
- Red Ink can also check texts against self-defined scripts and add work comments or create a review report (e.g., for standardized contract review or review of use cases against specific specifications). the scripts are easy to create;
- If you want to have a database of clauses or text blocks for your work, from which you can retrieve those that match your text or a topic, you can also do this with Red Ink;
- A web agent allows predefined processing of internet content (e.g. summarising the latest court decisions);
- Red Ink is able to automatically redact PDFs, with customizable Prompts
- In Excel, Red Ink can also be used to analyse large database tables (e.g. for processing a data breach) using AI;
- Finally, Red Ink also offers a local chat bot that provides access to all configured language models via any browser on the user's computer, even without logging in – ideal for researching or brainstorming outside of Word, Excel, or Outlook.
Is something missing? We are happy to check the implementation. Many new features have already been added this way. We want this to be the AI tool for Office with the most comprehensive and practical features. Like a big Swiss pocket knife.
Unlike some other offerings, Red Ink allows you to freely choose the AI provider you want to work with. If you don't trust any of these providers or they don't offer you the necessary assurances, you can also configure Red Ink to use a self-hosted LLM. The source code is open, and we have no access to your data. We don't want that either, because we originally developed the tool for ourselves. For the time being, we provide the tool for free. Since API access is also very cheap today, this solution is much less expensive to use for such applications than some other offers (often only a fraction). You have access to the latest and best language models, which can easily compete with specialized solutions (e.g., LegalTech).
Access occurs via a tile in the menu ribbon (and, depending on the configuration in Word and Excel, via the context menu or shortcuts; see the screenshot on the right). Various functions are already predefined, such as translating, abbreviating or correcting texts or summarising an email-chain. However, with ‘Freestyle’ you can enter any prompts you like, which are then applied to the selected text. You can also store a library of prompts and there are numerous options and configuration possibilities, e.g. the possibility of having the AI comment on the markup of the latest contract version you have received, merging two texts, accessing a library or the internet, or have a text revised or commented on using Word 'bubbles'. All this can be done directly from Word, Excel and Outlook, so there is no need to copy and paste between two windows.
Here is a demo video that shows what Red Ink can do for you less than five minutes:
Here is a video that shows how Red Ink kann be used to automatically complete a data protection impact assessment (DPIA). The video is in German, but the same also works in English.
Here you can download an extensive handbook with 70+ use cases on how you can use Red Ink in your daily work to increase your quality of work and efficiency using the tool: http://vischerlnk.com/redink-uc.
What do I need to run Red Ink?
Red Ink runs on Word, Excel and Outlook for Windows (Office for Mac cannot be supported for technical reasons).
All you need is so-called API access to a large language model (LLM), which you can either run yourself or, as is usually the case, access via the cloud. The tool supports API access from all common AI providers such as OpenAI, Microsoft and Google, as well as from local AI providers offering open source models, and Red Ink can also be used with self-hosted LLMs. API access is a technical access point to a language model directly for computers. Commercial providers charge for usage based on consumption, which is very inexpensive (usually significantly cheaper than subscriptions that charge a monthly fee per user) and therefore a much more attractive solution for many businesses, especially those with multiple users.
Using API access usually also allows you to protect data much better, because contracts are available for API access that are not offered for services for private users. This is how we do it at our law firm; for example, we have a special contract with Google for the Google Cloud Platform that allows us to use Red Ink with all data, including data subject to professional secrecy. This was not possible with conventional AI services.
In order to make AI accessible to business users with professional and official secrecy obligations, we have negotiated corresponding contract addenda with Google and other providers, which are now available to all relevant companies in Switzerland and, in some cases, in Germany. We have expanded our pre-existing model contract addendum for cloud providers to include a contract addendum for AI services (currently only available in German here) and have been able to convince several Swiss providers to offer their services with this addendum.
The following table provides an overview of various offers in the cloud and – for those who do not want to use the cloud – for local providers whose AI services can be used with Red Ink (these offers are not from us, we do not provide any warranties for them, nor do we warrant the following information, and we do not get any money if you obtain API access from one of these providers; everyone must check for themselves which one is right for them):
| Type | Provider | Description |
|---|---|---|
| Cloud | Advantage: Particularly powerful, versatile models Offering: Chatbot, app, API for multimodal models, text-to-speech, speech-to-text and image generation Location: Europe Data Processing Agreement: Yes Professional-/Official Secrecy Amendment: Yes, with contractual addendum (does not apply to search terms in internet searches) Zero data retention: Yes Abuse monitoring: Opt-out upon request How to get it: Online; details will follow as soon as the online process has been approved by Google (the necessary amendment has already been approved; its completion currently still requires a sales contact from Google). | |
| Cloud | Microsoft | Advantage: Particularly powerful, versatile models; many companies already have contracts with Microsoft Offer: Chatbot, app ("Copilot"), API for multimodal models, text-to-speech, speech-to-text and image generation Place of operation: Europe Data Processing Agreement: Yes, but not for use with internet searches Professional-/Official Secrecy Amendment: Yes, with contract addendum (does not apply to search terms for internet searches) Zero data retention: unclear Abuse monitoring: Opt-out only for customers directly supported by Microsoft (i.e. large customers) (API); no abuse monitoring for "Copilot" How to get it: Via distribution partners (so-called CSPs), according to this process (analogous to M365) Note: There are various versions of "Copilot" that offer different levels of protection, and it is often unclear to users which version they are dealing with. |
| Cloud | OpenAI | Advantage: Particularly powerful, versatile models Offer: Chatbot, app, API for multimodal models, text-to-speech, speech-to-text and image generation Place of operation: USA Data Processing Agreement: Yes Professional-/Official Secrecy Amendment: No, not interested (rejects requests) Zero data retention: Only for large customers Abuse monitoring: Takes place How to get it: Online |
| Switzerland | MTF | Advantage: Local provider, additional services Offer: API for open source language models (Llama 3) Location: Switzerland Data Processing Agreement: Yes Professional-/Official Secrecy Amendment: Yes Zero data retention: Yes Abuse monitoring: No How to get it: [email protected] |
| Switzerland | AlpineAI | Advantage: Local Provider, Comprehensive Swiss AI product suite, US-Cloud Act independent Swiss provider; Focus on highly regulated sectors (healthcare, government authorities) Offer: SwissGPT includes chat, speech-to-text, assistants, and agents, provider of API and customized GPT solutions Location: Switzerland, Davos & Zurich Data Processing Agreement: Yes Professional-/Official Secrecy Amendment: Yes Zero Data Retention: Yes Abuse Monitoring: No How to get it: Registration |
| Switzerland | Safe Swiss Cloud | Advantage: Local provider, additional services Offer: PAI Chat, PAI API, PAI Enterprise, PAI Developer, PAI Integration (MCP servers, etc.). Available models: Apertus 70 B (ETH/EPFL), DeepSeek 70 B & 670 B and others Place of operation: Switzerland Data Processing Agreement: Yes Professional-/Official Secrecy Amendment: Yes Zero data retention: Yes Abuse monitoring: Possible More information: https://safeswisscloud.com/en/private-ai/ How to get it: Contact Safe Swiss Cloud: Contact form |
Of course, there are other providers that may also be suitable. The list is not exhaustive and is not a recommendation or legal advice, but rather information we hope you find helpful. Compare the providers. If another Swiss provider is willing to sign a contract with our sample contract addendum, they should contact us. Any errors or suggested changes to the above table should also be reported to us. OpenAI is also welcome to contact us if it is willing to offer its services in compliance with professional and official secrecy regulations, or at least to discuss this (unlike Microsoft and Google, it has not done so to date). We will continue to monitor Microsoft closely due to the unsatisfactory situation regarding abuse monitoring opt-out and internet searches.
Not all of the models we use ourselves provide protection for professional and official secrecy data. It may be worthwhile to subscribe to additional models and services in order to benefit from models that are suitable for research purposes (e.g., AI-based Internet search, deep research), where special protection is often not an issue. Perplexity and OpenAI are popular choices in this area.
Where can I get help or training on how to use Red Ink?
To begin with, Red Ink is easy to install, even without IT knowledge. The easiest way to do this is to open the Edge browser (it must be this browser) on your Windows computer (Mac does not work) and go to https://apps.vischer.com. Click on the three large red buttons, confirm the security prompt, and the installation will run (you can also install the extension for the browser using the small button).
Then start Word and a configuration wizard will appear, which is prepared for the most common providers and asks you to enter the API data (we recommend obtaining an API key from OpenAI for a quick and inexpensive start). This configuration is then also used for the Excel and Outlook add-in. Later, when everything works, additional or other models and many other things can be configured.
All of this is described in the user manual and a quick guide in the manual with use cases. It also explains how to install it in a network with multiple users and centrally controlled configuration.
If you are unable to do this, please contact your IT service provider, who will find all the necessary information in the manual.
The following organisations offer training for Red Ink:
What are other specifications?
- The add-ins have English user dialogues, but can process texts, tables, etc. in all the languages supported by the respective LLM;
- The add-ins are developed as COM add-ins for Word, Excel and Outlook (but not the 'new' one) in VB.Net and are installed with an installer (available via https://apps.vischer.com); the add-ins have an update function
- Red Ink runs (only) on Windows;
- For certain additional functions (context menus, keyboard shortcuts, using the AI function of Red Ink from within your own Excel applications), the installation of helper add-ins in VBA (macros) for Word and Excel is required; however, Red Ink can also be used without them to a large extent;
- The source code of the add-ins is freely accessible (via GitHub, more than 20'000 lines of executable code); the compiled code is digitally signed by us for security reasons
- API access is via a https request (i.e. the transmission is encrypted);
- The add-ins can be extensively configured via a readable and editable configuration file – right down to the prompts they use for their functions; the configuration can be centralised and carried out by the users themselves;
- The Excel add-in has its own API that can be accessed by other Excel files (this makes it very easy to implement AI functions in other spreadsheets; see the example at the end);
- The API keys or private keys (for OAuth 2.0) can be protected with a light encryption;
- Users do not have to log-in;
- There is no logging or user access management (this has to be implemented separately);
- The browser extension requires a Chromium browser (Edge, Chrome, Firefox); Red Ink appears there in the context menu, provided it is not blocked by the respective application;
- The transcription function is currently based on the Vosk open-source models and the Whisper models from OpenAI and the cloud-based Google Speech-to-Text service (V1); no audio data is stored for legal reasons, but audio files can also be transcribed;
- The Google Text-to-Speech API or OpenAI's text-to-speech models are used used to generate speech (e.g. for creating podcasts and audiobooks) (requires a corresponding account);
- A prompt library with various sample prompts is included (some of which are from third parties).
- Any external information and database services can be connected, provided they have a JSON REST API; extensive configuration options are available for designing the query and processing the response.
Further information, in particular on functionality, can be found in the Red Ink user and installation guide.
What does Red Ink cost?
Nothing until the end of 2025. Red Ink was originally developed for internal use at VISCHER. However, due to high demand, the tool is also being made available to all other interested parties outside our law firm as part of the beta test, free of charge. This test phase will last until the end of 2025. The license is therefore limited until this date.
From 2026, Red Ink will be offered as a paid product. This decision is also a result of demand and the desire to put the solution on a broader footing and ensure its maintenance and further development. The revenue will enable the establishment of a development team that can maintain the software under the guidance of its author, David Rosenthal. The product is the software itself, i.e., the AI services, the IT support, and training must be procured separately. The price for the license (before any school and volume discounts) is expected to be CHF 8-9 per month per user (plus VAT) which, considering also the additional subscriptions required for one or more AI API services, to our knowledge, should be much more cost-effective than what is usually offered on the market for AI services for businesses. We want AI to be affordable to use; this is particularly helpful for the public sector and its procurement law requirements. In addition, the source code is open, which is also a common requirement in this area. Licensing will be handled through an online store that will be launched soon. We are working with IT and training partners to help companies and government agencies implement and use Red Ink. They also help set up API subscriptions for using the various AI services.
Private users will be able to use Red Ink for personal use free of charge until further notice.
In order to limit the use of the beta test versions beyond the test period, the add-ins have a date restriction. However, this restriction can be overridden via the configuration file as documented in the manual; users can also simply install the latest version of the add-ins. This should also be done by users whose version indicates that it expired on September 30, 2025 (this is because the beta test was originally scheduled to end on this date and these users have not updated their add-ins for some time).
Where can I get Red Ink?
Red Ink may be installed or downloaded from our deployment server: apps.vischer.com
Installation is done either by clicking on the red buttons (if your security settings allow it), or by downloading the installation package (this also contains sample files for centralized installation and configuration of additional services and various models). This is all described in detail in the user and installation instructions, along with the configuration and, of course, how to use the tool. The full-length recordings from the demo video and other content are also available on the deployment server. The source code is available on GitHub. Just go to review it to see what we are doing and which (open source) libraries we use, and if you want to compile it yourself for security reasons, you can do so, too.
What people say
Feeback we received internally and externally on Red Ink (Generation 1 and Generation 2):
"Beats Copilot by far"
"Very cool"
“Thanks again for this great tool, which brings me joy every day!”
"I am impressed by the latest developments at Red Ink - thank you for this and for sharing!"
"Wow!"
“The free add-in ‘RedInk’ by David Rosenthal is simply amazing. Every lawyer should try it out.”
“I am absolutely thrilled with how RedInk integrates artificial intelligence directly into Microsoft Word, Outlook, and Excel, completely without a browser and without copying back and forth. You simply stay in Office and still have access to the power of a large language model of your choice.”
"I tried to have ChatGPT create a markup. It told me it couldn't. Then I did it with Red Ink."
"I already use Red Ink daily and I'm a big fan!"
I used your Red Ink intensively for the first time in the last few days. To prepare a legal opinion on a license option agreement. It was enormously helpful!
"Red Ink, the AI tool for Microsoft Office that has significantly boosted my productivity here at VISCHER, is now available to everyone!"
"The program is brilliant! You don't have to upload anything, but can instruct directly from Word, Excel or Outlook, and as a layman, thanks to your preset commands, you are naturally guided to what you frequently need. The 'Quick Reference' is also a joy."
"Good that RedInk comes to the same conclusion as I did."
"I've been using your software more and more since the beginning of the year and I think it's really great."
"I think Red Ink is great. Very helpful when writing e-mails!"
"Wow. What Red [Ink] is capable of is really awesome. Not only in terms of textual quality, but also in terms of contextualized content."
"That rocks" (referring to the audio functions)
"Very cool – setting up a functioning Whisper on a PC is really tedious." (referring to the Transcriptor)
"We are currently creating possible logos for an event. We have worked intensively with Red Ink for this, which has worked very well."
In our experience, the most frequently used functions are those for translating and correcting and improving texts, the possibility of deep research through AI, the integration of external services, the browser extension for processing PDFs, the "bubbles" function and the chatbot that is directly integrated into Word. In Excel, Red Ink is often used to fill out forms.
Practical reports, blogs, posts, and interviews:
- Karin Graf, user report on “Red Ink,” seismOGraph No. 96 October 2025, pp. 19/20 (German only)
- Podcast “AI in everyday law firm life” by Recht. Intelligent with Daniel Brugger and Colin Carter, who talk to David Rosenthal about Red Ink in particular, including a demo (YouTube, Spotify), August 27, 2025 (German only)
- Podcast “LegalTech reloaded” by Boba Erbil, Digital Finance Planet, with David Rosenthal as guest on Red Ink and developments in the field of legal tech (Spotify), September 10, 2025 (German only)
- Podcast “Local Models and AI in Journalism” by Recht.Intelligent with Daniel Brugger and Colin Carter, who talk to Reto Vogt, starting at around minute 30, about Red Ink and how it can be operated with a local LLM (YouTube), October 2025 (German only)
- Daniel Brugger, Recht.Intelligent, on Red Ink on LinkedIn, September 2025 (German only)
Our company does not allow the installation of such software from unknown sources
It has good reasons for this! Malicious code could be hidden in the software, either intentionally or unintentionally. At least, Red Ink does not use Python, which draws on third-party software in an almost uncontrolled manner. But that does not change the fact that the software ultimately comes from a single developer whose main job is as a partner in a business law firm, not a professional software developer with a corresponding organisation.
Unfortunately, you will have to resolve the issue with your internal regulations yourself. We or I will not make any assurances and not fill out any questionnaires. However, the entire source code is openly available so that anyone can review it and form their own opinion. You can download it, check it out, and then compile it yourself to ensure that it does not contain anything you do not want.
This is also how certain companies with strict supplier management make use of it: They treat Red Ink as if it were their own development in terms of security. Different processes apply, and they usually offer more flexibility while maintaining the same level of security. This is because our software is not a black box and our solution is not a service, but only code.
Is there support?
Yes, to a limited extent. We are still a law firm and therefore do not offer the same support as a software company. But we are, of course, interested in maintaining and improving the tool. So, if you find a bug, have suggestions for improvements, or any other comments or questions, please let us know by emailing [email protected] or David Rosenthal (the author of Red Ink), or by providing input via GitHub. If you feel you need more support, please let us know and we will see what we can do for you.
It is very important that you ensure that you always use the latest version of the tool. If necessary, check this by clicking on the red buttons on https://apps.vischer.com/.
Is there a mailing list?
Yes, please register yourself below, if you want to be on the Red Ink mailing list. We will notify you if there is a new version or if there are other relevant developments. You can unsubscribe at any time using the link in the e-mails. You may also want to subscribe to our blogs, for example, on AI and Data & Privacy – or visit our collection of information and materials on AI law.
Is there more than Red Ink?
Yes, there is more!
Red Ink for Excel allows you to build additional applications that use AI more easily, as you can directly access the AI features of Red Ink from within other spreadsheets. For example, we have built the "Red Ink Analyzer", which is a contract and legal text analysis tool that is also open source and allows you to verify whether contracts, privacy notices etc. comply with certain requirements (which you can enter into the tool) and whether they have some other issues. The tool can also systematically search a collection of texts for specific content, which can be helpful for investigations, for example. The results can then be re-imported into a review tool like "Relativity". Another function is the intelligent comparison of texts.
The Red Ink Excel (and its helper module) add-in needs to be installed to use the "Red Ink Analzyer", and the Analyzer will use the LLM configured within the Red Ink add-in.
Here's a screenshot of the Red Ink Analyzer:
We have also built a tool with which our younger colleagues can practice negotiating contracts. With "Beat Inky!" the aim is to negotiate a clause in a dialogue with the AI and achieve the best possible result:
Furthermore, we have implemented solutions in which AI analyzes projects and provides an initial legal assessment, in order to relieve internal legal departments. Such a solution can, for example, provide an initial assessment of the AI Act:
Some of you may also already know or be using "VGPT", VISCHER's own AI client front-end tool, which is Excel based and can be configured for OpenAI's API and the API of Microsoft's Azure OpenAI Services. It is free and open source and can be downloaded here (as with Red Ink, it requires that digitally signed macros are enabled, it runs only on Windows and you need to have subscribed to a LLM endpoint).
Here's a screenshot of VGPT:
