Bidirectional Breadth-First Search (BFS)
A graph-search algorithm that expands outward from both the start and target nodes simultaneously and stops when the two search frontiers collide. For finding a path of depth d in a graph with branching factor b, this reduces the search space from O(bd) to O(bd/2) — for typical Roblox searches, roughly 10,000× faster than one-directional BFS. Algorithm writeup.
Degree of Separation
The number of friendship hops between two people in a social graph. If you're friends with someone directly, that's 1 degree. If your friend is friends with the target, you're 2 degrees away. The phrase comes from a 1929 short story by Frigyes Karinthy.
Small-World Network
A graph where most nodes aren't directly connected but any two random nodes are reachable through a small number of hops. Roblox's friend graph is a small-world network: average distance between any two active accounts is roughly 4 hops, comparable to Facebook's 3.57. More on Wikipedia.
Hub Account
An account with disproportionately many connections, acting as a bridge between otherwise disconnected groups. On Roblox, hub accounts include @david.baszucki, KreekCraft, DenisDaily, and other major creators. Hubs collapse the graph's effective diameter dramatically. Network-theory writeup.
Friend Graph
The full social network of Roblox accounts represented as a graph: each account is a node, each mutual friendship is an edge. FriendPath traverses this graph in real time to find shortest paths.
Frontier (BFS)
The set of nodes at the current "outer edge" of the search. Bidirectional BFS maintains two frontiers — one expanding from the start, one from the target — and detects collision when a node appears in both.
Builderman
The Roblox account at user ID 156. David Baszucki's developer-persona account, created February 27, 2006. The iconic construction-worker avatar. Has an empty public friends list by design. Full history.
DynaBlocks
The pre-launch name of Roblox, used from late 2003 through January 30, 2004. Roblox was also briefly called eBlocks and GoBlocks before settling on the final name. Origin story.
UK Online Safety Act (2023)
A UK law passed in October 2023 requiring online platforms to protect minors. Roblox responded by hiding friend lists for all UK-located accounts, which makes them invisible to graph-traversal tools like FriendPath. Detailed explainer.
Connections
Roblox's 2025 rebrand of the "Friends" system. The functionality is identical (mutual friend requests, same APIs), but the user-facing label changed alongside raising the cap from 200 to 1,000. What changed in 2026.
Rate Limit
A cap on how many API requests are allowed per IP per time window. Roblox's public friends API rate-limits aggressively per IP; FriendPath rotates across mirrored proxies to maintain high concurrency without getting blocked.
Six Degrees of Separation
The 1929 hypothesis (and subsequent 1967 Milgram experiment) that any two people on Earth are connected by no more than six handshakes. Facebook found 3.57 hops in its 1.6 billion-user graph in 2016. Apply to Roblox.
Server-Sent Events (SSE)
An HTTP streaming protocol where a server pushes data to the client over a long-lived connection. FriendPath uses SSE to send live progress updates ("depth 2", "frontier size 3,400", etc.) during a search.
Path Collision
The moment in bidirectional BFS when a node appears in both the forward and backward frontiers (or visited sets), indicating a complete path has been found. The path is reconstructed by walking back along both parent chains.
API Key
An authentication token used to access the metered FriendPath API. Format: ak_live_.... Issued through arbastro Suite. See API docs.
Visited Set
The collection of nodes the algorithm has already expanded. Tracking the visited set prevents infinite loops and is what makes BFS find the shortest path rather than just any path.
Proxy Rotation
The technique of cycling requests across multiple proxy endpoints to avoid per-IP rate limits. FriendPath rotates across several mirrored Roblox API proxies (roproxy.com, rotunnel.dev, etc.) to maintain ~250 concurrent in-flight friend-list requests.