Greasy Fork is available in English.
Icon next to the "Share" button (DeepSeek/ChatGPT) or in the send bar (Claude) to mark which system prompt(s) to add to the first message of each new conversation
Userscript (Tampermonkey / Violentmonkey) that adds a small 🐍 icon to DeepSeek, ChatGPT, and Claude from which you can mark which "system prompts" (behavior rules) you want to apply to the assistant, in the language of your choice. When you send your message, the script automatically adds the marked instructions just below, hidden beneath the scroll.
Current version: 0.3
deep_prompt.js, or open it directly if your manager allows it.No additional configuration or API keys are required.
When you enter any of the three sites you will see a small 🐍 icon next to a two-letter code (the active language, e.g. ES):
Hovering over it (or clicking to keep it pinned open) displays a panel with the available rules. Check the ones you want to apply and type your message normally: just before sending (when pressing Enter or the send button), the script adds the checked instructions at the end of your message, after a line break, so they don't visually interrupt what you wrote.
The script remembers, for the current conversation, which rules were active the last time you sent a message. On each send it compares that state with the current one:
From now on, follow the rule "Explain step by step": Explain your reasoning step by step, clearly and in detail, as if explaining it to someone without prior knowledge of the topic.
Cancel the rules "Explain step by step", "Be concise". The rest of the instructions I have given you remain in effect.
Both templates are translated into the 13 supported languages and are applied in the language you have selected at the time of sending.
When a truly new conversation is detected (no previous messages), the record resets.
The icon shows the code of the active language. Clicking on those letters opens a dropdown with the 13 available languages, each written in itself:
| Code | Language |
|---|---|
| ES | Español |
| CA | Català |
| EU | Euskara |
| GL | Galego |
| EN | English |
| FR | Français |
| DE | Deutsch |
| IT | Italiano |
| PT | Português |
| RU | Русский |
| ZH | 中文 |
| JA | 日本語 |
| KA | ქართული |
When you choose a language from the dropdown:
Each language includes, by default, four rules: Be concise, Explain step by step, Plain language, and Respond in [language] (to force the assistant to reply in that language even if you write to it in another).
Checking a rule on or off is done only by clicking its checkbox. Clicking the rule's name does something different: for your own custom rules, it loads that rule's name and text into the form at the bottom of the panel so you can edit it. The four built-in "factory" rules are read-only from the panel (their names are not clickable) — if you want a different version of one, create a personal copy as a custom rule and edit that instead of silently overwriting the original with no way to undo it.
Custom prompts are stored separately from the script's code, so they are not lost if you update the script to a new version in the future — only the "factory" prompts bundled in the file itself can change with an update.
At the bottom of the panel there is a row of icons (inline SVG, wireframe style) to recommend SyssPrompt to others, all pointing to the Greasy Fork page:
| Site | Icon anchor | Panel expansion |
|---|---|---|
| DeepSeek | Next to the "Share" button (top bar) | Downward |
| ChatGPT | Fixed, top-right corner | Downward |
| Claude | Fixed bottom right (not inserted into the page's DOM) | Upward |
The script automatically detects the text editor of each site (<textarea> on DeepSeek, contenteditable ProseMirror-type editor on ChatGPT and Claude) and inserts the text appropriately for each case, including the special handling required for these editors to register the change correctly.
If the pages change their internal structure in the future, the icon may stop finding its "anchor button" and stay in its fixed fallback position (always visible) until the selectors are adjusted in the code.
Inside the file you can adjust, among other things:
SITE_CONFIG: fixed position, expansion direction, and anchoring mode per site.PROMPTS_BY_LANG: the "factory" rules for each language (same id across all languages).UI_STRINGS: interface texts and the activation/deactivation templates, per language.LANGUAGE_NATIVE_NAMES: the names displayed in the language dropdown.SHARE_ICONS_SVG: the SVG icons in the "Share" row.PROMPT_JOIN / SEPARATOR: how rules are separated from each other and from your message.The script makes no network calls of its own and does not send data to any server (the "Share" links are the only ones that open an external URL, and only if you click on them). Everything it saves stays in your browser, via GM_setValue/GM_getValue (or localStorage if your manager does not support GM_*):
This data is shared between DeepSeek, ChatGPT, and Claude because it is the same script installed, but it does not leave your machine.
[SystemPrompt]) for more detail.input found: — if it points to a hidden or empty element, the text field selector may need adjustment (the site may have changed its HTML).[SystemPrompt] prefix.If you find it useful, there is a small support link at the bottom of the panel (non-intrusive, makes no network calls and collects no data). If you prefer not to see it, you can safely delete the block marked SUPPORT ... end SUPPORT block in the code; the rest of the script continues to work exactly the same.
GPL-3.0. Author: Francisco Vico.
