Directed acyclic graph

DAG, distributed acyclic graph, is a distributed-ledger technology that links transactions together directly without miners or blocks.

Currently (January 2018) there are three major DAG-based cryptocurrencies: Byteball, IOTA, and Raiblocks.

There is a wiki article comparing Byteball and IOTA.

Here is a table detailing differences among them. See the Cryptocurrency subreddit thread^[1] for further discussion.

Comparison

	Byteball	IOTA	Raiblocks/Nano
Address reuse	Yes	Not after sending	Yes
Chain type	Main chain DAG	PoW DAG	dPoS DAG+Blockchain
Confirmation time (theoretical)	30 seconds	Instant	Instant
Confirmation time (current)	~10 minutes?	Minutes to hours, to a day	~10 seconds

	Byteball	IOTA	Raiblocks
Address reuse	Yes	Not after sending	Yes
Chain type	Main chain DAG	PoW DAG	dPoS DAG+Blockchain
Confirmation time (theoretical)	30 seconds	Instant	Instant
Confirmation time (current)	~10 minutes?	Minutes to hours to a day?	~10 seconds
Consensus	Mainchain, deterministic	Minimal PoW, probabilistic	Weighted dPoS voting
Developer ownership	1%?	5%?	4.8%?
Distribution	Free airdrops, 1% premine	Public ICO. No premine	Manual mining via captcha
Distribution complete	No	Yes	Yes
Divisibility	1 GBYTE: 1 billion Bytes	1 MIOTA: 1 million IOTA	1 XRB: 10²⁴ raw
Fees	Very small, based on size of data stored	No fees	No fees
Focus	Smart contracts. Storing arbitrary data Value transfer	Internet of Things (m2m)	Value transfer (h2h)
Inflation	None/Deflationary (minus distribution)	None/Deflationary	None/Deflationary
Offline transactions	Via blackbytes?	Yes	Yes?
Partnerships	A few?	Many	None as of 2014?
Public team	Partially?	Yes	Yes
Privacy	Yes via Blackbytes	Eventually, Test mixer	Not on chain
Quantum resistant	Not yet. Via NTRU	Yes	No?
Smart contracts	Yes	Not yet?	No?
Supply (Current)	645,222 GBYTE	2,779,530,283 MIOTA	133,248,290 XRB
Supply (Total)	1,000,000 GBYTE	2,779,530,283 MIOTA	133,248,290 XRB
Transaction limit (theory)	Unlimited?	Unlimited	Unlimited
Transaction limit (current)	10 TPS	500 TPS in stress tests	7k TPS on Testnet?