Loading page
About this tool
Build mongodb:// and mongodb+srv:// URIs with replica set, auth source, read preference, write concern and TLS options.
This builder assembles a MongoDB connection URI in the official Connection String format — mongodb://user:password@host1:27017,host2:27017/db?options or the DNS seed list form mongodb+srv://cluster.example.mongodb.net/db — with credentials percent-encoded as the spec requires. It covers replicaSet, authSource, readPreference, write concern (w), tls, retryWrites, maxPoolSize and appName, and enforces the +srv rules: one host, no port. Everything is generated locally in the browser.
Open MongoDB Connection String Builder on AltFTool — it loads instantly in your browser.
Paste your code or data sample into the workspace.
Pick the format, conversion, or analysis you need.
Copy the polished result straight back into your project.
User names and passwords are percent-encoded exactly as the MongoDB connection string spec requires.
mongodb+srv:// is validated to a single host with no port, matching how DNS seed lists actually work.
Multiple host:port members, replicaSet, read preference and write concern handled in one form.
mongodb://user:password@host1:27017,host2:27017/defaultauthdb?replicaSet=rs0&authSource=admin — the default port is 27017, multiple replica-set members are comma-separated, and options follow as query parameters. The alternative mongodb+srv:// form names a single DNS host whose SRV records list the members.
mongodb:// lists every host explicitly, while mongodb+srv:// gives one DNS name and the driver discovers the members from SRV records — which is why +srv URIs must not include a port and take exactly one host. With +srv, TLS also defaults to enabled, which is the form MongoDB Atlas gives you.
Percent-encode them: the spec requires ':', '/', '?', '#', '[', ']', '@' and '%' in the user name or password to be percent-encoded, so p@ss/1 becomes p%40ss%2F1. Unencoded characters make the driver misparse the URI, which typically surfaces as an authentication or host-resolution error.
It tells the driver which database holds the user's credentials, independent of the database named in the URI path. Users created in the admin database need authSource=admin; if the option is omitted, the driver authenticates against the database in the path, or admin when no path database is given.