diff --git a/.env.sample b/.env.sample
index 5afdcbf8..d0092bd7 100644
--- a/.env.sample
+++ b/.env.sample
@@ -11,3 +11,13 @@ GITHUB_WEBHOOK_SECRET=MUST_BE_CONFIGURED
 # For example write blahblahblah here, if you want for this bot to
 # respond to @blahblahblah claim.
 # TRIAGEBOT_USERNAME=CAN_BE_CONFIGURED
+
+# Set your own Zulip instance (local testing only)
+# ZULIP_URL=https://testinstance.zulichat.com
+
+# Used for authenticating a bot
+# ZULIP_BOT_EMAIL=bot@testinstance.zulipchat.com
+# ZULIP_API_TOKEN=yyy
+
+# Authenticates inbound webhooks from Github
+# ZULIP_TOKEN=xxx
\ No newline at end of file
diff --git a/README.md b/README.md
index 436926bf..814b036f 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,10 @@ gh webhook forward --repo=ehuss/triagebot-test --events=* \
 
 Where the value in `--secret` is the secret value you place in `GITHUB_WEBHOOK_SECRET` in the `.env` file, and `--repo` is the repo you want to test against.
 
+### Zulip testing
+
+If you are modifying code that sends message to Zulip and want to test your changes, you can register a [new free Zulip instance](https://zulip.com/new/). Before launching the triagebot locally, set the Zulip env vars to connect to your test instance (see example in `.env.sample`).
+
 #### ngrok
 
 The following is an example of using <https://ngrok.com/> to provide webhook forwarding.
diff --git a/src/zulip.rs b/src/zulip.rs
index 8e77ab82..615670f8 100644
--- a/src/zulip.rs
+++ b/src/zulip.rs
@@ -9,8 +9,12 @@ use anyhow::{format_err, Context as _};
 use std::env;
 use std::fmt::Write as _;
 use std::str::FromStr;
+use std::sync::LazyLock;
 use tracing as log;
 
+static ZULIP_URL: LazyLock<String> =
+    LazyLock::new(|| env::var("ZULIP_URL").unwrap_or("https://rust-lang.zulipchat.com".into()));
+
 #[derive(Debug, serde::Deserialize)]
 pub struct Request {
     /// Markdown body of the sent message.
@@ -71,8 +75,6 @@ struct Response {
     content: String,
 }
 
-pub const BOT_EMAIL: &str = "triage-rust-lang-bot@zulipchat.com";
-
 pub async fn to_github_id(client: &GithubClient, zulip_id: u64) -> anyhow::Result<Option<u64>> {
     let map = crate::team_data::zulip_map(client).await?;
     Ok(map.users.get(&zulip_id).copied())
@@ -295,12 +297,14 @@ async fn execute_for_other_user(
         command
     };
     let bot_api_token = env::var("ZULIP_API_TOKEN").expect("ZULIP_API_TOKEN");
+    let bot_email =
+        env::var("ZULIP_BOT_EMAIL").unwrap_or("triage-rust-lang-bot@zulipchat.com".into());
 
     let members = ctx
         .github
         .raw()
-        .get("https://rust-lang.zulipchat.com/api/v1/users")
-        .basic_auth(BOT_EMAIL, Some(&bot_api_token))
+        .get(format!("{}/api/v1/users", *ZULIP_URL))
+        .basic_auth(bot_email, Some(&bot_api_token))
         .send()
         .await
         .map_err(|e| format_err!("Failed to get list of zulip users: {e:?}."))?;
@@ -414,7 +418,7 @@ impl Recipient<'_> {
     }
 
     pub fn url(&self) -> String {
-        format!("https://rust-lang.zulipchat.com/#narrow/{}", self.narrow())
+        format!("{}/#narrow/{}", *ZULIP_URL, self.narrow())
     }
 }
 
@@ -458,6 +462,8 @@ impl<'a> MessageApiRequest<'a> {
 
     pub async fn send(&self, client: &reqwest::Client) -> anyhow::Result<reqwest::Response> {
         let bot_api_token = env::var("ZULIP_API_TOKEN").expect("ZULIP_API_TOKEN");
+        let bot_email =
+            env::var("ZULIP_BOT_EMAIL").unwrap_or("triage-rust-lang-bot@zulipchat.com".into());
 
         #[derive(serde::Serialize)]
         struct SerializedApi<'a> {
@@ -470,8 +476,8 @@ impl<'a> MessageApiRequest<'a> {
         }
 
         Ok(client
-            .post("https://rust-lang.zulipchat.com/api/v1/messages")
-            .basic_auth(BOT_EMAIL, Some(&bot_api_token))
+            .post(format!("{}/api/v1/messages", *ZULIP_URL))
+            .basic_auth(bot_email, Some(&bot_api_token))
             .form(&SerializedApi {
                 type_: match self.recipient {
                     Recipient::Stream { .. } => "stream",
@@ -509,6 +515,8 @@ pub struct UpdateMessageApiRequest<'a> {
 impl<'a> UpdateMessageApiRequest<'a> {
     pub async fn send(&self, client: &reqwest::Client) -> anyhow::Result<reqwest::Response> {
         let bot_api_token = env::var("ZULIP_API_TOKEN").expect("ZULIP_API_TOKEN");
+        let bot_email =
+            env::var("ZULIP_BOT_EMAIL").unwrap_or("triage-rust-lang-bot@zulipchat.com".into());
 
         #[derive(serde::Serialize)]
         struct SerializedApi<'a> {
@@ -522,10 +530,10 @@ impl<'a> UpdateMessageApiRequest<'a> {
 
         Ok(client
             .patch(&format!(
-                "https://rust-lang.zulipchat.com/api/v1/messages/{}",
-                self.message_id
+                "{}/api/v1/messages/{}",
+                *ZULIP_URL, self.message_id
             ))
-            .basic_auth(BOT_EMAIL, Some(&bot_api_token))
+            .basic_auth(bot_email, Some(&bot_api_token))
             .form(&SerializedApi {
                 topic: self.topic,
                 propagate_mode: self.propagate_mode,
@@ -712,13 +720,15 @@ struct AddReaction<'a> {
 impl<'a> AddReaction<'a> {
     pub async fn send(self, client: &reqwest::Client) -> anyhow::Result<reqwest::Response> {
         let bot_api_token = env::var("ZULIP_API_TOKEN").expect("ZULIP_API_TOKEN");
+        let bot_email =
+            env::var("ZULIP_BOT_EMAIL").unwrap_or("triage-rust-lang-bot@zulipchat.com".into());
 
         Ok(client
             .post(&format!(
-                "https://rust-lang.zulipchat.com/api/v1/messages/{}/reactions",
-                self.message_id
+                "{}/api/v1/messages/{}/reactions",
+                *ZULIP_URL, self.message_id
             ))
-            .basic_auth(BOT_EMAIL, Some(&bot_api_token))
+            .basic_auth(bot_email, Some(&bot_api_token))
             .form(&self)
             .send()
             .await?)